v3.25.1
Shareholder Report
 6 Months Ended
Feb. 28, 2025
USD ($)
Holding
Shareholder Report [Line Items]  
Document Type N-CSRS
Amendment Flag false
Registrant Name MFS SERIES TRUST I
Entity Central Index Key 0000798244
Entity Investment Company Type N-1A
Document Period End Date Feb. 28, 2025
C000002179 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® U.S. Government Cash Reserve Fund
Class Name Class A
Trading Symbol MSRXX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS U.S. Government Cash Reserve Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
A $21 0.42%
Expenses Paid, Amount $ 21
Expense Ratio, Percent 0.42%
Net Assets $ 475,673,395
Holdings Count | Holding 19
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 475,673,395
Total Number of Holdings: 19
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
U.S. Treasury and U.S. Government Agency Securities and Equivalents 66.9%
Repurchase Agreements, collateralized by U.S. Treasury and/or U.S. Government Agency Securities 33.1%
Composition including fixed income credit quality
A-1+ 61.8%
A-1 38.2%
Maturity breakdown
0 - 7 days 37.0%
8 - 29 days 19.7%
30 - 59 days 25.7%
60 - 89 days 12.8%
90 - 365 days 4.8%
Ratings are assigned to portfolio securities utilizing ratings from Moody’s, Fitch, and Standard & Poor’s rating agencies and applying the following hierarchy: If all three agencies provide a rating, the middle rating (after dropping the highest and lowest ratings) is assigned; if two of the three agencies rate a security, the lower of the two is assigned. Ratings are shown in the S&P scale. All ratings are subject to change. The fund did not hold unrated securities. The fund is not rated by these agencies.
Credit Ratings Selection [Text Block]
Ratings are assigned to portfolio securities utilizing ratings from Moody’s, Fitch, and Standard & Poor’s rating agencies and applying the following hierarchy: If all three agencies provide a rating, the middle rating (after dropping the highest and lowest ratings) is assigned; if two of the three agencies rate a security, the lower of the two is assigned. Ratings are shown in the S&P scale. All ratings are subject to change. The fund did not hold unrated securities. The fund is not rated by these agencies.
C000002182 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® U.S. Government Cash Reserve Fund
Class Name Class B
Trading Symbol MCRXX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS U.S. Government Cash Reserve Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
B $21 0.42%
Expenses Paid, Amount $ 21
Expense Ratio, Percent 0.42%
Net Assets $ 475,673,395
Holdings Count | Holding 19
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 475,673,395
Total Number of Holdings: 19
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
U.S. Treasury and U.S. Government Agency Securities and Equivalents 66.9%
Repurchase Agreements, collateralized by U.S. Treasury and/or U.S. Government Agency Securities 33.1%
Composition including fixed income credit quality
A-1+ 61.8%
A-1 38.2%
Maturity breakdown
0 - 7 days 37.0%
8 - 29 days 19.7%
30 - 59 days 25.7%
60 - 89 days 12.8%
90 - 365 days 4.8%
Ratings are assigned to portfolio securities utilizing ratings from Moody’s, Fitch, and Standard & Poor’s rating agencies and applying the following hierarchy: If all three agencies provide a rating, the middle rating (after dropping the highest and lowest ratings) is assigned; if two of the three agencies rate a security, the lower of the two is assigned. Ratings are shown in the S&P scale. All ratings are subject to change. The fund did not hold unrated securities. The fund is not rated by these agencies.
Credit Ratings Selection [Text Block]
Ratings are assigned to portfolio securities utilizing ratings from Moody’s, Fitch, and Standard & Poor’s rating agencies and applying the following hierarchy: If all three agencies provide a rating, the middle rating (after dropping the highest and lowest ratings) is assigned; if two of the three agencies rate a security, the lower of the two is assigned. Ratings are shown in the S&P scale. All ratings are subject to change. The fund did not hold unrated securities. The fund is not rated by these agencies.
C000002183 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® U.S. Government Cash Reserve Fund
Class Name Class C
Trading Symbol MCCXX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS U.S. Government Cash Reserve Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
C $21 0.42%
Expenses Paid, Amount $ 21
Expense Ratio, Percent 0.42%
Net Assets $ 475,673,395
Holdings Count | Holding 19
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 475,673,395
Total Number of Holdings: 19
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
U.S. Treasury and U.S. Government Agency Securities and Equivalents 66.9%
Repurchase Agreements, collateralized by U.S. Treasury and/or U.S. Government Agency Securities 33.1%
Composition including fixed income credit quality
A-1+ 61.8%
A-1 38.2%
Maturity breakdown
0 - 7 days 37.0%
8 - 29 days 19.7%
30 - 59 days 25.7%
60 - 89 days 12.8%
90 - 365 days 4.8%
Ratings are assigned to portfolio securities utilizing ratings from Moody’s, Fitch, and Standard & Poor’s rating agencies and applying the following hierarchy: If all three agencies provide a rating, the middle rating (after dropping the highest and lowest ratings) is assigned; if two of the three agencies rate a security, the lower of the two is assigned. Ratings are shown in the S&P scale. All ratings are subject to change. The fund did not hold unrated securities. The fund is not rated by these agencies.
Credit Ratings Selection [Text Block]
Ratings are assigned to portfolio securities utilizing ratings from Moody’s, Fitch, and Standard & Poor’s rating agencies and applying the following hierarchy: If all three agencies provide a rating, the middle rating (after dropping the highest and lowest ratings) is assigned; if two of the three agencies rate a security, the lower of the two is assigned. Ratings are shown in the S&P scale. All ratings are subject to change. The fund did not hold unrated securities. The fund is not rated by these agencies.
C000206005 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® U.S. Government Cash Reserve Fund
Class Name Class I
Trading Symbol CRHXX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS U.S. Government Cash Reserve Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
I $21 0.42%
Expenses Paid, Amount $ 21
Expense Ratio, Percent 0.42%
Net Assets $ 475,673,395
Holdings Count | Holding 19
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 475,673,395
Total Number of Holdings: 19
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
U.S. Treasury and U.S. Government Agency Securities and Equivalents 66.9%
Repurchase Agreements, collateralized by U.S. Treasury and/or U.S. Government Agency Securities 33.1%
Composition including fixed income credit quality
A-1+ 61.8%
A-1 38.2%
Maturity breakdown
0 - 7 days 37.0%
8 - 29 days 19.7%
30 - 59 days 25.7%
60 - 89 days 12.8%
90 - 365 days 4.8%
Ratings are assigned to portfolio securities utilizing ratings from Moody’s, Fitch, and Standard & Poor’s rating agencies and applying the following hierarchy: If all three agencies provide a rating, the middle rating (after dropping the highest and lowest ratings) is assigned; if two of the three agencies rate a security, the lower of the two is assigned. Ratings are shown in the S&P scale. All ratings are subject to change. The fund did not hold unrated securities. The fund is not rated by these agencies.
Credit Ratings Selection [Text Block]
Ratings are assigned to portfolio securities utilizing ratings from Moody’s, Fitch, and Standard & Poor’s rating agencies and applying the following hierarchy: If all three agencies provide a rating, the middle rating (after dropping the highest and lowest ratings) is assigned; if two of the three agencies rate a security, the lower of the two is assigned. Ratings are shown in the S&P scale. All ratings are subject to change. The fund did not hold unrated securities. The fund is not rated by these agencies.
C000002184 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® U.S. Government Cash Reserve Fund
Class Name Class R1
Trading Symbol CRVXX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS U.S. Government Cash Reserve Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R1 $21 0.42%
Expenses Paid, Amount $ 21
Expense Ratio, Percent 0.42%
Net Assets $ 475,673,395
Holdings Count | Holding 19
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 475,673,395
Total Number of Holdings: 19
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
U.S. Treasury and U.S. Government Agency Securities and Equivalents 66.9%
Repurchase Agreements, collateralized by U.S. Treasury and/or U.S. Government Agency Securities 33.1%
Composition including fixed income credit quality
A-1+ 61.8%
A-1 38.2%
Maturity breakdown
0 - 7 days 37.0%
8 - 29 days 19.7%
30 - 59 days 25.7%
60 - 89 days 12.8%
90 - 365 days 4.8%
Ratings are assigned to portfolio securities utilizing ratings from Moody’s, Fitch, and Standard & Poor’s rating agencies and applying the following hierarchy: If all three agencies provide a rating, the middle rating (after dropping the highest and lowest ratings) is assigned; if two of the three agencies rate a security, the lower of the two is assigned. Ratings are shown in the S&P scale. All ratings are subject to change. The fund did not hold unrated securities. The fund is not rated by these agencies.
Credit Ratings Selection [Text Block]
Ratings are assigned to portfolio securities utilizing ratings from Moody’s, Fitch, and Standard & Poor’s rating agencies and applying the following hierarchy: If all three agencies provide a rating, the middle rating (after dropping the highest and lowest ratings) is assigned; if two of the three agencies rate a security, the lower of the two is assigned. Ratings are shown in the S&P scale. All ratings are subject to change. The fund did not hold unrated securities. The fund is not rated by these agencies.
C000002186 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® U.S. Government Cash Reserve Fund
Class Name Class R2
Trading Symbol CRMXX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS U.S. Government Cash Reserve Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R2 $21 0.42%
Expenses Paid, Amount $ 21
Expense Ratio, Percent 0.42%
Net Assets $ 475,673,395
Holdings Count | Holding 19
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 475,673,395
Total Number of Holdings: 19
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
U.S. Treasury and U.S. Government Agency Securities and Equivalents 66.9%
Repurchase Agreements, collateralized by U.S. Treasury and/or U.S. Government Agency Securities 33.1%
Composition including fixed income credit quality
A-1+ 61.8%
A-1 38.2%
Maturity breakdown
0 - 7 days 37.0%
8 - 29 days 19.7%
30 - 59 days 25.7%
60 - 89 days 12.8%
90 - 365 days 4.8%
Ratings are assigned to portfolio securities utilizing ratings from Moody’s, Fitch, and Standard & Poor’s rating agencies and applying the following hierarchy: If all three agencies provide a rating, the middle rating (after dropping the highest and lowest ratings) is assigned; if two of the three agencies rate a security, the lower of the two is assigned. Ratings are shown in the S&P scale. All ratings are subject to change. The fund did not hold unrated securities. The fund is not rated by these agencies.
Credit Ratings Selection [Text Block]
Ratings are assigned to portfolio securities utilizing ratings from Moody’s, Fitch, and Standard & Poor’s rating agencies and applying the following hierarchy: If all three agencies provide a rating, the middle rating (after dropping the highest and lowest ratings) is assigned; if two of the three agencies rate a security, the lower of the two is assigned. Ratings are shown in the S&P scale. All ratings are subject to change. The fund did not hold unrated securities. The fund is not rated by these agencies.
C000002187 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® U.S. Government Cash Reserve Fund
Class Name Class R3
Trading Symbol CRJXX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS U.S. Government Cash Reserve Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R3 $21 0.42%
Expenses Paid, Amount $ 21
Expense Ratio, Percent 0.42%
Net Assets $ 475,673,395
Holdings Count | Holding 19
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 475,673,395
Total Number of Holdings: 19
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
U.S. Treasury and U.S. Government Agency Securities and Equivalents 66.9%
Repurchase Agreements, collateralized by U.S. Treasury and/or U.S. Government Agency Securities 33.1%
Composition including fixed income credit quality
A-1+ 61.8%
A-1 38.2%
Maturity breakdown
0 - 7 days 37.0%
8 - 29 days 19.7%
30 - 59 days 25.7%
60 - 89 days 12.8%
90 - 365 days 4.8%
Ratings are assigned to portfolio securities utilizing ratings from Moody’s, Fitch, and Standard & Poor’s rating agencies and applying the following hierarchy: If all three agencies provide a rating, the middle rating (after dropping the highest and lowest ratings) is assigned; if two of the three agencies rate a security, the lower of the two is assigned. Ratings are shown in the S&P scale. All ratings are subject to change. The fund did not hold unrated securities. The fund is not rated by these agencies.
Credit Ratings Selection [Text Block]
Ratings are assigned to portfolio securities utilizing ratings from Moody’s, Fitch, and Standard & Poor’s rating agencies and applying the following hierarchy: If all three agencies provide a rating, the middle rating (after dropping the highest and lowest ratings) is assigned; if two of the three agencies rate a security, the lower of the two is assigned. Ratings are shown in the S&P scale. All ratings are subject to change. The fund did not hold unrated securities. The fund is not rated by these agencies.
C000002188 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® U.S. Government Cash Reserve Fund
Class Name Class R4
Trading Symbol CRKXX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS U.S. Government Cash Reserve Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R4 $21 0.42%
Expenses Paid, Amount $ 21
Expense Ratio, Percent 0.42%
Net Assets $ 475,673,395
Holdings Count | Holding 19
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 475,673,395
Total Number of Holdings: 19
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
U.S. Treasury and U.S. Government Agency Securities and Equivalents 66.9%
Repurchase Agreements, collateralized by U.S. Treasury and/or U.S. Government Agency Securities 33.1%
Composition including fixed income credit quality
A-1+ 61.8%
A-1 38.2%
Maturity breakdown
0 - 7 days 37.0%
8 - 29 days 19.7%
30 - 59 days 25.7%
60 - 89 days 12.8%
90 - 365 days 4.8%
Ratings are assigned to portfolio securities utilizing ratings from Moody’s, Fitch, and Standard & Poor’s rating agencies and applying the following hierarchy: If all three agencies provide a rating, the middle rating (after dropping the highest and lowest ratings) is assigned; if two of the three agencies rate a security, the lower of the two is assigned. Ratings are shown in the S&P scale. All ratings are subject to change. The fund did not hold unrated securities. The fund is not rated by these agencies.
Credit Ratings Selection [Text Block]
Ratings are assigned to portfolio securities utilizing ratings from Moody’s, Fitch, and Standard & Poor’s rating agencies and applying the following hierarchy: If all three agencies provide a rating, the middle rating (after dropping the highest and lowest ratings) is assigned; if two of the three agencies rate a security, the lower of the two is assigned. Ratings are shown in the S&P scale. All ratings are subject to change. The fund did not hold unrated securities. The fund is not rated by these agencies.
C000206004 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® U.S. Government Cash Reserve Fund
Class Name Class R6
Trading Symbol CRRXX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS U.S. Government Cash Reserve Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R6 $19 0.37%
Expenses Paid, Amount $ 19
Expense Ratio, Percent 0.37%
Net Assets $ 475,673,395
Holdings Count | Holding 19
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 475,673,395
Total Number of Holdings: 19
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
U.S. Treasury and U.S. Government Agency Securities and Equivalents 66.9%
Repurchase Agreements, collateralized by U.S. Treasury and/or U.S. Government Agency Securities 33.1%
Composition including fixed income credit quality
A-1+ 61.8%
A-1 38.2%
Maturity breakdown
0 - 7 days 37.0%
8 - 29 days 19.7%
30 - 59 days 25.7%
60 - 89 days 12.8%
90 - 365 days 4.8%
Ratings are assigned to portfolio securities utilizing ratings from Moody’s, Fitch, and Standard & Poor’s rating agencies and applying the following hierarchy: If all three agencies provide a rating, the middle rating (after dropping the highest and lowest ratings) is assigned; if two of the three agencies rate a security, the lower of the two is assigned. Ratings are shown in the S&P scale. All ratings are subject to change. The fund did not hold unrated securities. The fund is not rated by these agencies.
Credit Ratings Selection [Text Block]
Ratings are assigned to portfolio securities utilizing ratings from Moody’s, Fitch, and Standard & Poor’s rating agencies and applying the following hierarchy: If all three agencies provide a rating, the middle rating (after dropping the highest and lowest ratings) is assigned; if two of the three agencies rate a security, the lower of the two is assigned. Ratings are shown in the S&P scale. All ratings are subject to change. The fund did not hold unrated securities. The fund is not rated by these agencies.
C000002190 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Core Equity Fund
Class Name Class A
Trading Symbol MRGAX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Core Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
A $45 0.88%
Expenses Paid, Amount $ 45
Expense Ratio, Percent 0.88%
Net Assets $ 6,624,975,483
Holdings Count | Holding 192
Investment Company Portfolio Turnover 18.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 6,624,975,483 Portfolio Turnover Rate (%): 18
Total Number of Holdings: 192
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 100.1%
Money Market Funds 0.0%
Securities Sold Short (0.1)%
Global equity sectors
Technology 29.5%
Financial Services 14.7%
Capital Goods 13.5%
Health Care 11.7%
Consumer Cyclicals 11.5%
Communication Services 9.4%
Energy 6.1%
Consumer Staples 3.6%
Top ten holdings
Microsoft Corp. 6.1%
Amazon.com, Inc. 4.8%
NVIDIA Corp. 4.2%
Meta Platforms, Inc., "A" 3.0%
Alphabet, Inc., "A" 3.0%
Apple, Inc. 2.5%
JPMorgan Chase & Co. 2.0%
Visa, Inc., "A" 1.9%
Johnson & Johnson 1.6%
AbbVie, Inc. 1.5%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 6.1%
Amazon.com, Inc. 4.8%
NVIDIA Corp. 4.2%
Meta Platforms, Inc., "A" 3.0%
Alphabet, Inc., "A" 3.0%
Apple, Inc. 2.5%
JPMorgan Chase & Co. 2.0%
Visa, Inc., "A" 1.9%
Johnson & Johnson 1.6%
AbbVie, Inc. 1.5%
C000002192 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Core Equity Fund
Class Name Class B
Trading Symbol MRGBX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Core Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
B $83 1.63%
Expenses Paid, Amount $ 83
Expense Ratio, Percent 1.63%
Net Assets $ 6,624,975,483
Holdings Count | Holding 192
Investment Company Portfolio Turnover 18.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 6,624,975,483 Portfolio Turnover Rate (%): 18
Total Number of Holdings: 192
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 100.1%
Money Market Funds 0.0%
Securities Sold Short (0.1)%
Global equity sectors
Technology 29.5%
Financial Services 14.7%
Capital Goods 13.5%
Health Care 11.7%
Consumer Cyclicals 11.5%
Communication Services 9.4%
Energy 6.1%
Consumer Staples 3.6%
Top ten holdings
Microsoft Corp. 6.1%
Amazon.com, Inc. 4.8%
NVIDIA Corp. 4.2%
Meta Platforms, Inc., "A" 3.0%
Alphabet, Inc., "A" 3.0%
Apple, Inc. 2.5%
JPMorgan Chase & Co. 2.0%
Visa, Inc., "A" 1.9%
Johnson & Johnson 1.6%
AbbVie, Inc. 1.5%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 6.1%
Amazon.com, Inc. 4.8%
NVIDIA Corp. 4.2%
Meta Platforms, Inc., "A" 3.0%
Alphabet, Inc., "A" 3.0%
Apple, Inc. 2.5%
JPMorgan Chase & Co. 2.0%
Visa, Inc., "A" 1.9%
Johnson & Johnson 1.6%
AbbVie, Inc. 1.5%
C000002193 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Core Equity Fund
Class Name Class C
Trading Symbol MRGCX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Core Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
C $83 1.63%
Expenses Paid, Amount $ 83
Expense Ratio, Percent 1.63%
Net Assets $ 6,624,975,483
Holdings Count | Holding 192
Investment Company Portfolio Turnover 18.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 6,624,975,483 Portfolio Turnover Rate (%): 18
Total Number of Holdings: 192
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 100.1%
Money Market Funds 0.0%
Securities Sold Short (0.1)%
Global equity sectors
Technology 29.5%
Financial Services 14.7%
Capital Goods 13.5%
Health Care 11.7%
Consumer Cyclicals 11.5%
Communication Services 9.4%
Energy 6.1%
Consumer Staples 3.6%
Top ten holdings
Microsoft Corp. 6.1%
Amazon.com, Inc. 4.8%
NVIDIA Corp. 4.2%
Meta Platforms, Inc., "A" 3.0%
Alphabet, Inc., "A" 3.0%
Apple, Inc. 2.5%
JPMorgan Chase & Co. 2.0%
Visa, Inc., "A" 1.9%
Johnson & Johnson 1.6%
AbbVie, Inc. 1.5%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 6.1%
Amazon.com, Inc. 4.8%
NVIDIA Corp. 4.2%
Meta Platforms, Inc., "A" 3.0%
Alphabet, Inc., "A" 3.0%
Apple, Inc. 2.5%
JPMorgan Chase & Co. 2.0%
Visa, Inc., "A" 1.9%
Johnson & Johnson 1.6%
AbbVie, Inc. 1.5%
C000002194 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Core Equity Fund
Class Name Class I
Trading Symbol MRGRX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Core Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
I $32 0.63%
Expenses Paid, Amount $ 32
Expense Ratio, Percent 0.63%
Net Assets $ 6,624,975,483
Holdings Count | Holding 192
Investment Company Portfolio Turnover 18.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 6,624,975,483 Portfolio Turnover Rate (%): 18
Total Number of Holdings: 192
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 100.1%
Money Market Funds 0.0%
Securities Sold Short (0.1)%
Global equity sectors
Technology 29.5%
Financial Services 14.7%
Capital Goods 13.5%
Health Care 11.7%
Consumer Cyclicals 11.5%
Communication Services 9.4%
Energy 6.1%
Consumer Staples 3.6%
Top ten holdings
Microsoft Corp. 6.1%
Amazon.com, Inc. 4.8%
NVIDIA Corp. 4.2%
Meta Platforms, Inc., "A" 3.0%
Alphabet, Inc., "A" 3.0%
Apple, Inc. 2.5%
JPMorgan Chase & Co. 2.0%
Visa, Inc., "A" 1.9%
Johnson & Johnson 1.6%
AbbVie, Inc. 1.5%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 6.1%
Amazon.com, Inc. 4.8%
NVIDIA Corp. 4.2%
Meta Platforms, Inc., "A" 3.0%
Alphabet, Inc., "A" 3.0%
Apple, Inc. 2.5%
JPMorgan Chase & Co. 2.0%
Visa, Inc., "A" 1.9%
Johnson & Johnson 1.6%
AbbVie, Inc. 1.5%
C000002196 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Core Equity Fund
Class Name Class R1
Trading Symbol MRGGX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Core Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R1 $83 1.63%
Expenses Paid, Amount $ 83
Expense Ratio, Percent 1.63%
Net Assets $ 6,624,975,483
Holdings Count | Holding 192
Investment Company Portfolio Turnover 18.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 6,624,975,483 Portfolio Turnover Rate (%): 18
Total Number of Holdings: 192
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 100.1%
Money Market Funds 0.0%
Securities Sold Short (0.1)%
Global equity sectors
Technology 29.5%
Financial Services 14.7%
Capital Goods 13.5%
Health Care 11.7%
Consumer Cyclicals 11.5%
Communication Services 9.4%
Energy 6.1%
Consumer Staples 3.6%
Top ten holdings
Microsoft Corp. 6.1%
Amazon.com, Inc. 4.8%
NVIDIA Corp. 4.2%
Meta Platforms, Inc., "A" 3.0%
Alphabet, Inc., "A" 3.0%
Apple, Inc. 2.5%
JPMorgan Chase & Co. 2.0%
Visa, Inc., "A" 1.9%
Johnson & Johnson 1.6%
AbbVie, Inc. 1.5%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 6.1%
Amazon.com, Inc. 4.8%
NVIDIA Corp. 4.2%
Meta Platforms, Inc., "A" 3.0%
Alphabet, Inc., "A" 3.0%
Apple, Inc. 2.5%
JPMorgan Chase & Co. 2.0%
Visa, Inc., "A" 1.9%
Johnson & Johnson 1.6%
AbbVie, Inc. 1.5%
C000002198 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Core Equity Fund
Class Name Class R2
Trading Symbol MRERX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Core Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R2 $57 1.13%
Expenses Paid, Amount $ 57
Expense Ratio, Percent 1.13%
Net Assets $ 6,624,975,483
Holdings Count | Holding 192
Investment Company Portfolio Turnover 18.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 6,624,975,483 Portfolio Turnover Rate (%): 18
Total Number of Holdings: 192
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 100.1%
Money Market Funds 0.0%
Securities Sold Short (0.1)%
Global equity sectors
Technology 29.5%
Financial Services 14.7%
Capital Goods 13.5%
Health Care 11.7%
Consumer Cyclicals 11.5%
Communication Services 9.4%
Energy 6.1%
Consumer Staples 3.6%
Top ten holdings
Microsoft Corp. 6.1%
Amazon.com, Inc. 4.8%
NVIDIA Corp. 4.2%
Meta Platforms, Inc., "A" 3.0%
Alphabet, Inc., "A" 3.0%
Apple, Inc. 2.5%
JPMorgan Chase & Co. 2.0%
Visa, Inc., "A" 1.9%
Johnson & Johnson 1.6%
AbbVie, Inc. 1.5%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 6.1%
Amazon.com, Inc. 4.8%
NVIDIA Corp. 4.2%
Meta Platforms, Inc., "A" 3.0%
Alphabet, Inc., "A" 3.0%
Apple, Inc. 2.5%
JPMorgan Chase & Co. 2.0%
Visa, Inc., "A" 1.9%
Johnson & Johnson 1.6%
AbbVie, Inc. 1.5%
C000002199 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Core Equity Fund
Class Name Class R3
Trading Symbol MRGHX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Core Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R3 $45 0.88%
Expenses Paid, Amount $ 45
Expense Ratio, Percent 0.88%
Net Assets $ 6,624,975,483
Holdings Count | Holding 192
Investment Company Portfolio Turnover 18.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 6,624,975,483 Portfolio Turnover Rate (%): 18
Total Number of Holdings: 192
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 100.1%
Money Market Funds 0.0%
Securities Sold Short (0.1)%
Global equity sectors
Technology 29.5%
Financial Services 14.7%
Capital Goods 13.5%
Health Care 11.7%
Consumer Cyclicals 11.5%
Communication Services 9.4%
Energy 6.1%
Consumer Staples 3.6%
Top ten holdings
Microsoft Corp. 6.1%
Amazon.com, Inc. 4.8%
NVIDIA Corp. 4.2%
Meta Platforms, Inc., "A" 3.0%
Alphabet, Inc., "A" 3.0%
Apple, Inc. 2.5%
JPMorgan Chase & Co. 2.0%
Visa, Inc., "A" 1.9%
Johnson & Johnson 1.6%
AbbVie, Inc. 1.5%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 6.1%
Amazon.com, Inc. 4.8%
NVIDIA Corp. 4.2%
Meta Platforms, Inc., "A" 3.0%
Alphabet, Inc., "A" 3.0%
Apple, Inc. 2.5%
JPMorgan Chase & Co. 2.0%
Visa, Inc., "A" 1.9%
Johnson & Johnson 1.6%
AbbVie, Inc. 1.5%
C000002191 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Core Equity Fund
Class Name Class R4
Trading Symbol MRGJX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Core Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R4 $32 0.63%
Expenses Paid, Amount $ 32
Expense Ratio, Percent 0.63%
Net Assets $ 6,624,975,483
Holdings Count | Holding 192
Investment Company Portfolio Turnover 18.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 6,624,975,483 Portfolio Turnover Rate (%): 18
Total Number of Holdings: 192
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 100.1%
Money Market Funds 0.0%
Securities Sold Short (0.1)%
Global equity sectors
Technology 29.5%
Financial Services 14.7%
Capital Goods 13.5%
Health Care 11.7%
Consumer Cyclicals 11.5%
Communication Services 9.4%
Energy 6.1%
Consumer Staples 3.6%
Top ten holdings
Microsoft Corp. 6.1%
Amazon.com, Inc. 4.8%
NVIDIA Corp. 4.2%
Meta Platforms, Inc., "A" 3.0%
Alphabet, Inc., "A" 3.0%
Apple, Inc. 2.5%
JPMorgan Chase & Co. 2.0%
Visa, Inc., "A" 1.9%
Johnson & Johnson 1.6%
AbbVie, Inc. 1.5%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 6.1%
Amazon.com, Inc. 4.8%
NVIDIA Corp. 4.2%
Meta Platforms, Inc., "A" 3.0%
Alphabet, Inc., "A" 3.0%
Apple, Inc. 2.5%
JPMorgan Chase & Co. 2.0%
Visa, Inc., "A" 1.9%
Johnson & Johnson 1.6%
AbbVie, Inc. 1.5%
C000124424 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Core Equity Fund
Class Name Class R6
Trading Symbol MRGKX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Core Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R6 $28 0.55%
Expenses Paid, Amount $ 28
Expense Ratio, Percent 0.55%
Net Assets $ 6,624,975,483
Holdings Count | Holding 192
Investment Company Portfolio Turnover 18.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 6,624,975,483 Portfolio Turnover Rate (%): 18
Total Number of Holdings: 192
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 100.1%
Money Market Funds 0.0%
Securities Sold Short (0.1)%
Global equity sectors
Technology 29.5%
Financial Services 14.7%
Capital Goods 13.5%
Health Care 11.7%
Consumer Cyclicals 11.5%
Communication Services 9.4%
Energy 6.1%
Consumer Staples 3.6%
Top ten holdings
Microsoft Corp. 6.1%
Amazon.com, Inc. 4.8%
NVIDIA Corp. 4.2%
Meta Platforms, Inc., "A" 3.0%
Alphabet, Inc., "A" 3.0%
Apple, Inc. 2.5%
JPMorgan Chase & Co. 2.0%
Visa, Inc., "A" 1.9%
Johnson & Johnson 1.6%
AbbVie, Inc. 1.5%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 6.1%
Amazon.com, Inc. 4.8%
NVIDIA Corp. 4.2%
Meta Platforms, Inc., "A" 3.0%
Alphabet, Inc., "A" 3.0%
Apple, Inc. 2.5%
JPMorgan Chase & Co. 2.0%
Visa, Inc., "A" 1.9%
Johnson & Johnson 1.6%
AbbVie, Inc. 1.5%
C000002210 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® New Discovery Fund
Class Name Class A
Trading Symbol MNDAX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS New Discovery Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
A $62 1.27%
Expenses Paid, Amount $ 62
Expense Ratio, Percent 1.27%
Net Assets $ 2,085,239,585
Holdings Count | Holding 115
Investment Company Portfolio Turnover 32.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 2,085,239,585 Portfolio Turnover Rate (%): 32
Total Number of Holdings: 115
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 96.1%
Money Market Funds 3.9%
Equity sectors
Health Care 25.3%
Industrials 20.0%
Information Technology 18.9%
Consumer Discretionary 10.2%
Financials 7.5%
Energy 4.9%
Real Estate 3.4%
Consumer Staples 3.2%
Materials 2.4%
Communication Services 0.3%
Top ten holdings
RB Global, Inc. 2.1%
Crane Co. 2.0%
U.S. Foods Holding Corp. 1.8%
CACI International, Inc., "A" 1.7%
Independence Realty Trust, Inc., REIT 1.6%
Flowserve Corp. 1.6%
Genius Sports Ltd. 1.6%
Schrodinger, Inc. 1.6%
SentinelOne, Inc., "A" 1.5%
Hamilton Lane, Inc., "A" 1.4%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
RB Global, Inc. 2.1%
Crane Co. 2.0%
U.S. Foods Holding Corp. 1.8%
CACI International, Inc., "A" 1.7%
Independence Realty Trust, Inc., REIT 1.6%
Flowserve Corp. 1.6%
Genius Sports Ltd. 1.6%
Schrodinger, Inc. 1.6%
SentinelOne, Inc., "A" 1.5%
Hamilton Lane, Inc., "A" 1.4%
C000002215 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® New Discovery Fund
Class Name Class B
Trading Symbol MNDBX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS New Discovery Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
B $99 2.02%
Expenses Paid, Amount $ 99
Expense Ratio, Percent 2.02%
Net Assets $ 2,085,239,585
Holdings Count | Holding 115
Investment Company Portfolio Turnover 32.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 2,085,239,585 Portfolio Turnover Rate (%): 32
Total Number of Holdings: 115
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 96.1%
Money Market Funds 3.9%
Equity sectors
Health Care 25.3%
Industrials 20.0%
Information Technology 18.9%
Consumer Discretionary 10.2%
Financials 7.5%
Energy 4.9%
Real Estate 3.4%
Consumer Staples 3.2%
Materials 2.4%
Communication Services 0.3%
Top ten holdings
RB Global, Inc. 2.1%
Crane Co. 2.0%
U.S. Foods Holding Corp. 1.8%
CACI International, Inc., "A" 1.7%
Independence Realty Trust, Inc., REIT 1.6%
Flowserve Corp. 1.6%
Genius Sports Ltd. 1.6%
Schrodinger, Inc. 1.6%
SentinelOne, Inc., "A" 1.5%
Hamilton Lane, Inc., "A" 1.4%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
RB Global, Inc. 2.1%
Crane Co. 2.0%
U.S. Foods Holding Corp. 1.8%
CACI International, Inc., "A" 1.7%
Independence Realty Trust, Inc., REIT 1.6%
Flowserve Corp. 1.6%
Genius Sports Ltd. 1.6%
Schrodinger, Inc. 1.6%
SentinelOne, Inc., "A" 1.5%
Hamilton Lane, Inc., "A" 1.4%
C000002216 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® New Discovery Fund
Class Name Class C
Trading Symbol MNDCX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS New Discovery Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
C $99 2.02%
Expenses Paid, Amount $ 99
Expense Ratio, Percent 2.02%
Net Assets $ 2,085,239,585
Holdings Count | Holding 115
Investment Company Portfolio Turnover 32.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 2,085,239,585 Portfolio Turnover Rate (%): 32
Total Number of Holdings: 115
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 96.1%
Money Market Funds 3.9%
Equity sectors
Health Care 25.3%
Industrials 20.0%
Information Technology 18.9%
Consumer Discretionary 10.2%
Financials 7.5%
Energy 4.9%
Real Estate 3.4%
Consumer Staples 3.2%
Materials 2.4%
Communication Services 0.3%
Top ten holdings
RB Global, Inc. 2.1%
Crane Co. 2.0%
U.S. Foods Holding Corp. 1.8%
CACI International, Inc., "A" 1.7%
Independence Realty Trust, Inc., REIT 1.6%
Flowserve Corp. 1.6%
Genius Sports Ltd. 1.6%
Schrodinger, Inc. 1.6%
SentinelOne, Inc., "A" 1.5%
Hamilton Lane, Inc., "A" 1.4%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
RB Global, Inc. 2.1%
Crane Co. 2.0%
U.S. Foods Holding Corp. 1.8%
CACI International, Inc., "A" 1.7%
Independence Realty Trust, Inc., REIT 1.6%
Flowserve Corp. 1.6%
Genius Sports Ltd. 1.6%
Schrodinger, Inc. 1.6%
SentinelOne, Inc., "A" 1.5%
Hamilton Lane, Inc., "A" 1.4%
C000002217 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® New Discovery Fund
Class Name Class I
Trading Symbol MNDIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS New Discovery Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
I $50 1.02%
Expenses Paid, Amount $ 50
Expense Ratio, Percent 1.02%
Net Assets $ 2,085,239,585
Holdings Count | Holding 115
Investment Company Portfolio Turnover 32.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 2,085,239,585 Portfolio Turnover Rate (%): 32
Total Number of Holdings: 115
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 96.1%
Money Market Funds 3.9%
Equity sectors
Health Care 25.3%
Industrials 20.0%
Information Technology 18.9%
Consumer Discretionary 10.2%
Financials 7.5%
Energy 4.9%
Real Estate 3.4%
Consumer Staples 3.2%
Materials 2.4%
Communication Services 0.3%
Top ten holdings
RB Global, Inc. 2.1%
Crane Co. 2.0%
U.S. Foods Holding Corp. 1.8%
CACI International, Inc., "A" 1.7%
Independence Realty Trust, Inc., REIT 1.6%
Flowserve Corp. 1.6%
Genius Sports Ltd. 1.6%
Schrodinger, Inc. 1.6%
SentinelOne, Inc., "A" 1.5%
Hamilton Lane, Inc., "A" 1.4%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
RB Global, Inc. 2.1%
Crane Co. 2.0%
U.S. Foods Holding Corp. 1.8%
CACI International, Inc., "A" 1.7%
Independence Realty Trust, Inc., REIT 1.6%
Flowserve Corp. 1.6%
Genius Sports Ltd. 1.6%
Schrodinger, Inc. 1.6%
SentinelOne, Inc., "A" 1.5%
Hamilton Lane, Inc., "A" 1.4%
C000002219 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® New Discovery Fund
Class Name Class R1
Trading Symbol MNDGX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS New Discovery Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R1 $99 2.02%
Expenses Paid, Amount $ 99
Expense Ratio, Percent 2.02%
Net Assets $ 2,085,239,585
Holdings Count | Holding 115
Investment Company Portfolio Turnover 32.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 2,085,239,585 Portfolio Turnover Rate (%): 32
Total Number of Holdings: 115
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 96.1%
Money Market Funds 3.9%
Equity sectors
Health Care 25.3%
Industrials 20.0%
Information Technology 18.9%
Consumer Discretionary 10.2%
Financials 7.5%
Energy 4.9%
Real Estate 3.4%
Consumer Staples 3.2%
Materials 2.4%
Communication Services 0.3%
Top ten holdings
RB Global, Inc. 2.1%
Crane Co. 2.0%
U.S. Foods Holding Corp. 1.8%
CACI International, Inc., "A" 1.7%
Independence Realty Trust, Inc., REIT 1.6%
Flowserve Corp. 1.6%
Genius Sports Ltd. 1.6%
Schrodinger, Inc. 1.6%
SentinelOne, Inc., "A" 1.5%
Hamilton Lane, Inc., "A" 1.4%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
RB Global, Inc. 2.1%
Crane Co. 2.0%
U.S. Foods Holding Corp. 1.8%
CACI International, Inc., "A" 1.7%
Independence Realty Trust, Inc., REIT 1.6%
Flowserve Corp. 1.6%
Genius Sports Ltd. 1.6%
Schrodinger, Inc. 1.6%
SentinelOne, Inc., "A" 1.5%
Hamilton Lane, Inc., "A" 1.4%
C000002221 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® New Discovery Fund
Class Name Class R2
Trading Symbol MNDRX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS New Discovery Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R2 $75 1.52%
Expenses Paid, Amount $ 75
Expense Ratio, Percent 1.52%
Net Assets $ 2,085,239,585
Holdings Count | Holding 115
Investment Company Portfolio Turnover 32.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 2,085,239,585 Portfolio Turnover Rate (%): 32
Total Number of Holdings: 115
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 96.1%
Money Market Funds 3.9%
Equity sectors
Health Care 25.3%
Industrials 20.0%
Information Technology 18.9%
Consumer Discretionary 10.2%
Financials 7.5%
Energy 4.9%
Real Estate 3.4%
Consumer Staples 3.2%
Materials 2.4%
Communication Services 0.3%
Top ten holdings
RB Global, Inc. 2.1%
Crane Co. 2.0%
U.S. Foods Holding Corp. 1.8%
CACI International, Inc., "A" 1.7%
Independence Realty Trust, Inc., REIT 1.6%
Flowserve Corp. 1.6%
Genius Sports Ltd. 1.6%
Schrodinger, Inc. 1.6%
SentinelOne, Inc., "A" 1.5%
Hamilton Lane, Inc., "A" 1.4%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
RB Global, Inc. 2.1%
Crane Co. 2.0%
U.S. Foods Holding Corp. 1.8%
CACI International, Inc., "A" 1.7%
Independence Realty Trust, Inc., REIT 1.6%
Flowserve Corp. 1.6%
Genius Sports Ltd. 1.6%
Schrodinger, Inc. 1.6%
SentinelOne, Inc., "A" 1.5%
Hamilton Lane, Inc., "A" 1.4%
C000002222 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® New Discovery Fund
Class Name Class R3
Trading Symbol MNDHX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS New Discovery Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R3 $62 1.27%
Expenses Paid, Amount $ 62
Expense Ratio, Percent 1.27%
Net Assets $ 2,085,239,585
Holdings Count | Holding 115
Investment Company Portfolio Turnover 32.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 2,085,239,585 Portfolio Turnover Rate (%): 32
Total Number of Holdings: 115
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 96.1%
Money Market Funds 3.9%
Equity sectors
Health Care 25.3%
Industrials 20.0%
Information Technology 18.9%
Consumer Discretionary 10.2%
Financials 7.5%
Energy 4.9%
Real Estate 3.4%
Consumer Staples 3.2%
Materials 2.4%
Communication Services 0.3%
Top ten holdings
RB Global, Inc. 2.1%
Crane Co. 2.0%
U.S. Foods Holding Corp. 1.8%
CACI International, Inc., "A" 1.7%
Independence Realty Trust, Inc., REIT 1.6%
Flowserve Corp. 1.6%
Genius Sports Ltd. 1.6%
Schrodinger, Inc. 1.6%
SentinelOne, Inc., "A" 1.5%
Hamilton Lane, Inc., "A" 1.4%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
RB Global, Inc. 2.1%
Crane Co. 2.0%
U.S. Foods Holding Corp. 1.8%
CACI International, Inc., "A" 1.7%
Independence Realty Trust, Inc., REIT 1.6%
Flowserve Corp. 1.6%
Genius Sports Ltd. 1.6%
Schrodinger, Inc. 1.6%
SentinelOne, Inc., "A" 1.5%
Hamilton Lane, Inc., "A" 1.4%
C000002211 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® New Discovery Fund
Class Name Class R4
Trading Symbol MNDJX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS New Discovery Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R4 $50 1.02%
Expenses Paid, Amount $ 50
Expense Ratio, Percent 1.02%
Net Assets $ 2,085,239,585
Holdings Count | Holding 115
Investment Company Portfolio Turnover 32.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 2,085,239,585 Portfolio Turnover Rate (%): 32
Total Number of Holdings: 115
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 96.1%
Money Market Funds 3.9%
Equity sectors
Health Care 25.3%
Industrials 20.0%
Information Technology 18.9%
Consumer Discretionary 10.2%
Financials 7.5%
Energy 4.9%
Real Estate 3.4%
Consumer Staples 3.2%
Materials 2.4%
Communication Services 0.3%
Top ten holdings
RB Global, Inc. 2.1%
Crane Co. 2.0%
U.S. Foods Holding Corp. 1.8%
CACI International, Inc., "A" 1.7%
Independence Realty Trust, Inc., REIT 1.6%
Flowserve Corp. 1.6%
Genius Sports Ltd. 1.6%
Schrodinger, Inc. 1.6%
SentinelOne, Inc., "A" 1.5%
Hamilton Lane, Inc., "A" 1.4%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
RB Global, Inc. 2.1%
Crane Co. 2.0%
U.S. Foods Holding Corp. 1.8%
CACI International, Inc., "A" 1.7%
Independence Realty Trust, Inc., REIT 1.6%
Flowserve Corp. 1.6%
Genius Sports Ltd. 1.6%
Schrodinger, Inc. 1.6%
SentinelOne, Inc., "A" 1.5%
Hamilton Lane, Inc., "A" 1.4%
C000075013 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® New Discovery Fund
Class Name Class R6
Trading Symbol MNDKX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS New Discovery Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R6 $44 0.89%
Expenses Paid, Amount $ 44
Expense Ratio, Percent 0.89%
Net Assets $ 2,085,239,585
Holdings Count | Holding 115
Investment Company Portfolio Turnover 32.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 2,085,239,585 Portfolio Turnover Rate (%): 32
Total Number of Holdings: 115
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 96.1%
Money Market Funds 3.9%
Equity sectors
Health Care 25.3%
Industrials 20.0%
Information Technology 18.9%
Consumer Discretionary 10.2%
Financials 7.5%
Energy 4.9%
Real Estate 3.4%
Consumer Staples 3.2%
Materials 2.4%
Communication Services 0.3%
Top ten holdings
RB Global, Inc. 2.1%
Crane Co. 2.0%
U.S. Foods Holding Corp. 1.8%
CACI International, Inc., "A" 1.7%
Independence Realty Trust, Inc., REIT 1.6%
Flowserve Corp. 1.6%
Genius Sports Ltd. 1.6%
Schrodinger, Inc. 1.6%
SentinelOne, Inc., "A" 1.5%
Hamilton Lane, Inc., "A" 1.4%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
RB Global, Inc. 2.1%
Crane Co. 2.0%
U.S. Foods Holding Corp. 1.8%
CACI International, Inc., "A" 1.7%
Independence Realty Trust, Inc., REIT 1.6%
Flowserve Corp. 1.6%
Genius Sports Ltd. 1.6%
Schrodinger, Inc. 1.6%
SentinelOne, Inc., "A" 1.5%
Hamilton Lane, Inc., "A" 1.4%
C000002223 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Research International Fund
Class Name Class A
Trading Symbol MRSAX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Research International Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
A $48 0.99%
Expenses Paid, Amount $ 48
Expense Ratio, Percent 0.99%
Net Assets $ 16,297,524,207
Holdings Count | Holding 110
Investment Company Portfolio Turnover 10.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 16,297,524,207 Portfolio Turnover Rate (%): 10
Total Number of Holdings: 110
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 98.6%
Money Market Funds 1.4%
Top ten holdings
Schneider Electric SE 3.5%
Linde PLC 2.9%
Roche Holding AG 2.9%
Hitachi Ltd. 2.4%
Novo Nordisk A.S., "B" 2.4%
Nestle S.A. 2.3%
LVMH Moet Hennessy Louis Vuitton SE 2.1%
NatWest Group PLC 1.9%
Barclays PLC 1.8%
Aon PLC 1.8%
Issuer country weightings
Japan 17.5%
France 14.4%
United Kingdom 13.1%
United States 10.3%
Switzerland 8.8%
Germany 5.8%
Netherlands 5.0%
Australia 3.1%
Denmark 3.0%
Other Countries 19.0%
Largest Holdings [Text Block]
Top ten holdings
Schneider Electric SE 3.5%
Linde PLC 2.9%
Roche Holding AG 2.9%
Hitachi Ltd. 2.4%
Novo Nordisk A.S., "B" 2.4%
Nestle S.A. 2.3%
LVMH Moet Hennessy Louis Vuitton SE 2.1%
NatWest Group PLC 1.9%
Barclays PLC 1.8%
Aon PLC 1.8%
C000002228 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Research International Fund
Class Name Class B
Trading Symbol MRIBX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Research International Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
B $85 1.74%
Expenses Paid, Amount $ 85
Expense Ratio, Percent 1.74%
Net Assets $ 16,297,524,207
Holdings Count | Holding 110
Investment Company Portfolio Turnover 10.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 16,297,524,207 Portfolio Turnover Rate (%): 10
Total Number of Holdings: 110
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 98.6%
Money Market Funds 1.4%
Top ten holdings
Schneider Electric SE 3.5%
Linde PLC 2.9%
Roche Holding AG 2.9%
Hitachi Ltd. 2.4%
Novo Nordisk A.S., "B" 2.4%
Nestle S.A. 2.3%
LVMH Moet Hennessy Louis Vuitton SE 2.1%
NatWest Group PLC 1.9%
Barclays PLC 1.8%
Aon PLC 1.8%
Issuer country weightings
Japan 17.5%
France 14.4%
United Kingdom 13.1%
United States 10.3%
Switzerland 8.8%
Germany 5.8%
Netherlands 5.0%
Australia 3.1%
Denmark 3.0%
Other Countries 19.0%
Largest Holdings [Text Block]
Top ten holdings
Schneider Electric SE 3.5%
Linde PLC 2.9%
Roche Holding AG 2.9%
Hitachi Ltd. 2.4%
Novo Nordisk A.S., "B" 2.4%
Nestle S.A. 2.3%
LVMH Moet Hennessy Louis Vuitton SE 2.1%
NatWest Group PLC 1.9%
Barclays PLC 1.8%
Aon PLC 1.8%
C000002229 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Research International Fund
Class Name Class C
Trading Symbol MRICX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Research International Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
C $85 1.74%
Expenses Paid, Amount $ 85
Expense Ratio, Percent 1.74%
Net Assets $ 16,297,524,207
Holdings Count | Holding 110
Investment Company Portfolio Turnover 10.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 16,297,524,207 Portfolio Turnover Rate (%): 10
Total Number of Holdings: 110
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 98.6%
Money Market Funds 1.4%
Top ten holdings
Schneider Electric SE 3.5%
Linde PLC 2.9%
Roche Holding AG 2.9%
Hitachi Ltd. 2.4%
Novo Nordisk A.S., "B" 2.4%
Nestle S.A. 2.3%
LVMH Moet Hennessy Louis Vuitton SE 2.1%
NatWest Group PLC 1.9%
Barclays PLC 1.8%
Aon PLC 1.8%
Issuer country weightings
Japan 17.5%
France 14.4%
United Kingdom 13.1%
United States 10.3%
Switzerland 8.8%
Germany 5.8%
Netherlands 5.0%
Australia 3.1%
Denmark 3.0%
Other Countries 19.0%
Largest Holdings [Text Block]
Top ten holdings
Schneider Electric SE 3.5%
Linde PLC 2.9%
Roche Holding AG 2.9%
Hitachi Ltd. 2.4%
Novo Nordisk A.S., "B" 2.4%
Nestle S.A. 2.3%
LVMH Moet Hennessy Louis Vuitton SE 2.1%
NatWest Group PLC 1.9%
Barclays PLC 1.8%
Aon PLC 1.8%
C000002230 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Research International Fund
Class Name Class I
Trading Symbol MRSIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Research International Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
I $36 0.74%
Expenses Paid, Amount $ 36
Expense Ratio, Percent 0.74%
Net Assets $ 16,297,524,207
Holdings Count | Holding 110
Investment Company Portfolio Turnover 10.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 16,297,524,207 Portfolio Turnover Rate (%): 10
Total Number of Holdings: 110
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 98.6%
Money Market Funds 1.4%
Top ten holdings
Schneider Electric SE 3.5%
Linde PLC 2.9%
Roche Holding AG 2.9%
Hitachi Ltd. 2.4%
Novo Nordisk A.S., "B" 2.4%
Nestle S.A. 2.3%
LVMH Moet Hennessy Louis Vuitton SE 2.1%
NatWest Group PLC 1.9%
Barclays PLC 1.8%
Aon PLC 1.8%
Issuer country weightings
Japan 17.5%
France 14.4%
United Kingdom 13.1%
United States 10.3%
Switzerland 8.8%
Germany 5.8%
Netherlands 5.0%
Australia 3.1%
Denmark 3.0%
Other Countries 19.0%
Largest Holdings [Text Block]
Top ten holdings
Schneider Electric SE 3.5%
Linde PLC 2.9%
Roche Holding AG 2.9%
Hitachi Ltd. 2.4%
Novo Nordisk A.S., "B" 2.4%
Nestle S.A. 2.3%
LVMH Moet Hennessy Louis Vuitton SE 2.1%
NatWest Group PLC 1.9%
Barclays PLC 1.8%
Aon PLC 1.8%
C000002232 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Research International Fund
Class Name Class R1
Trading Symbol MRSGX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Research International Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R1 $85 1.74%
Expenses Paid, Amount $ 85
Expense Ratio, Percent 1.74%
Net Assets $ 16,297,524,207
Holdings Count | Holding 110
Investment Company Portfolio Turnover 10.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 16,297,524,207 Portfolio Turnover Rate (%): 10
Total Number of Holdings: 110
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 98.6%
Money Market Funds 1.4%
Top ten holdings
Schneider Electric SE 3.5%
Linde PLC 2.9%
Roche Holding AG 2.9%
Hitachi Ltd. 2.4%
Novo Nordisk A.S., "B" 2.4%
Nestle S.A. 2.3%
LVMH Moet Hennessy Louis Vuitton SE 2.1%
NatWest Group PLC 1.9%
Barclays PLC 1.8%
Aon PLC 1.8%
Issuer country weightings
Japan 17.5%
France 14.4%
United Kingdom 13.1%
United States 10.3%
Switzerland 8.8%
Germany 5.8%
Netherlands 5.0%
Australia 3.1%
Denmark 3.0%
Other Countries 19.0%
Largest Holdings [Text Block]
Top ten holdings
Schneider Electric SE 3.5%
Linde PLC 2.9%
Roche Holding AG 2.9%
Hitachi Ltd. 2.4%
Novo Nordisk A.S., "B" 2.4%
Nestle S.A. 2.3%
LVMH Moet Hennessy Louis Vuitton SE 2.1%
NatWest Group PLC 1.9%
Barclays PLC 1.8%
Aon PLC 1.8%
C000002234 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Research International Fund
Class Name Class R2
Trading Symbol MRSRX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Research International Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R2 $61 1.24%
Expenses Paid, Amount $ 61
Expense Ratio, Percent 1.24%
Net Assets $ 16,297,524,207
Holdings Count | Holding 110
Investment Company Portfolio Turnover 10.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 16,297,524,207 Portfolio Turnover Rate (%): 10
Total Number of Holdings: 110
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 98.6%
Money Market Funds 1.4%
Top ten holdings
Schneider Electric SE 3.5%
Linde PLC 2.9%
Roche Holding AG 2.9%
Hitachi Ltd. 2.4%
Novo Nordisk A.S., "B" 2.4%
Nestle S.A. 2.3%
LVMH Moet Hennessy Louis Vuitton SE 2.1%
NatWest Group PLC 1.9%
Barclays PLC 1.8%
Aon PLC 1.8%
Issuer country weightings
Japan 17.5%
France 14.4%
United Kingdom 13.1%
United States 10.3%
Switzerland 8.8%
Germany 5.8%
Netherlands 5.0%
Australia 3.1%
Denmark 3.0%
Other Countries 19.0%
Largest Holdings [Text Block]
Top ten holdings
Schneider Electric SE 3.5%
Linde PLC 2.9%
Roche Holding AG 2.9%
Hitachi Ltd. 2.4%
Novo Nordisk A.S., "B" 2.4%
Nestle S.A. 2.3%
LVMH Moet Hennessy Louis Vuitton SE 2.1%
NatWest Group PLC 1.9%
Barclays PLC 1.8%
Aon PLC 1.8%
C000002235 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Research International Fund
Class Name Class R3
Trading Symbol MRSHX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Research International Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R3 $48 0.99%
Expenses Paid, Amount $ 48
Expense Ratio, Percent 0.99%
Net Assets $ 16,297,524,207
Holdings Count | Holding 110
Investment Company Portfolio Turnover 10.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 16,297,524,207 Portfolio Turnover Rate (%): 10
Total Number of Holdings: 110
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 98.6%
Money Market Funds 1.4%
Top ten holdings
Schneider Electric SE 3.5%
Linde PLC 2.9%
Roche Holding AG 2.9%
Hitachi Ltd. 2.4%
Novo Nordisk A.S., "B" 2.4%
Nestle S.A. 2.3%
LVMH Moet Hennessy Louis Vuitton SE 2.1%
NatWest Group PLC 1.9%
Barclays PLC 1.8%
Aon PLC 1.8%
Issuer country weightings
Japan 17.5%
France 14.4%
United Kingdom 13.1%
United States 10.3%
Switzerland 8.8%
Germany 5.8%
Netherlands 5.0%
Australia 3.1%
Denmark 3.0%
Other Countries 19.0%
Largest Holdings [Text Block]
Top ten holdings
Schneider Electric SE 3.5%
Linde PLC 2.9%
Roche Holding AG 2.9%
Hitachi Ltd. 2.4%
Novo Nordisk A.S., "B" 2.4%
Nestle S.A. 2.3%
LVMH Moet Hennessy Louis Vuitton SE 2.1%
NatWest Group PLC 1.9%
Barclays PLC 1.8%
Aon PLC 1.8%
C000002224 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Research International Fund
Class Name Class R4
Trading Symbol MRSJX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Research International Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R4 $36 0.74%
Expenses Paid, Amount $ 36
Expense Ratio, Percent 0.74%
Net Assets $ 16,297,524,207
Holdings Count | Holding 110
Investment Company Portfolio Turnover 10.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 16,297,524,207 Portfolio Turnover Rate (%): 10
Total Number of Holdings: 110
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 98.6%
Money Market Funds 1.4%
Top ten holdings
Schneider Electric SE 3.5%
Linde PLC 2.9%
Roche Holding AG 2.9%
Hitachi Ltd. 2.4%
Novo Nordisk A.S., "B" 2.4%
Nestle S.A. 2.3%
LVMH Moet Hennessy Louis Vuitton SE 2.1%
NatWest Group PLC 1.9%
Barclays PLC 1.8%
Aon PLC 1.8%
Issuer country weightings
Japan 17.5%
France 14.4%
United Kingdom 13.1%
United States 10.3%
Switzerland 8.8%
Germany 5.8%
Netherlands 5.0%
Australia 3.1%
Denmark 3.0%
Other Countries 19.0%
Largest Holdings [Text Block]
Top ten holdings
Schneider Electric SE 3.5%
Linde PLC 2.9%
Roche Holding AG 2.9%
Hitachi Ltd. 2.4%
Novo Nordisk A.S., "B" 2.4%
Nestle S.A. 2.3%
LVMH Moet Hennessy Louis Vuitton SE 2.1%
NatWest Group PLC 1.9%
Barclays PLC 1.8%
Aon PLC 1.8%
C000034436 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Research International Fund
Class Name Class R6
Trading Symbol MRSKX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Research International Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R6 $31 0.64%
Expenses Paid, Amount $ 31
Expense Ratio, Percent 0.64%
Net Assets $ 16,297,524,207
Holdings Count | Holding 110
Investment Company Portfolio Turnover 10.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 16,297,524,207 Portfolio Turnover Rate (%): 10
Total Number of Holdings: 110
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 98.6%
Money Market Funds 1.4%
Top ten holdings
Schneider Electric SE 3.5%
Linde PLC 2.9%
Roche Holding AG 2.9%
Hitachi Ltd. 2.4%
Novo Nordisk A.S., "B" 2.4%
Nestle S.A. 2.3%
LVMH Moet Hennessy Louis Vuitton SE 2.1%
NatWest Group PLC 1.9%
Barclays PLC 1.8%
Aon PLC 1.8%
Issuer country weightings
Japan 17.5%
France 14.4%
United Kingdom 13.1%
United States 10.3%
Switzerland 8.8%
Germany 5.8%
Netherlands 5.0%
Australia 3.1%
Denmark 3.0%
Other Countries 19.0%
Largest Holdings [Text Block]
Top ten holdings
Schneider Electric SE 3.5%
Linde PLC 2.9%
Roche Holding AG 2.9%
Hitachi Ltd. 2.4%
Novo Nordisk A.S., "B" 2.4%
Nestle S.A. 2.3%
LVMH Moet Hennessy Louis Vuitton SE 2.1%
NatWest Group PLC 1.9%
Barclays PLC 1.8%
Aon PLC 1.8%
C000002249 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Technology Fund
Class Name Class A
Trading Symbol MTCAX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Technology Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
A $57 1.10%
Expenses Paid, Amount $ 57
Expense Ratio, Percent 1.10%
Net Assets $ 2,053,482,986
Holdings Count | Holding 57
Investment Company Portfolio Turnover 26.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 2,053,482,986 Portfolio Turnover Rate (%): 26
Total Number of Holdings: 57
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 98.7%
Money Market Funds 1.3%
Top ten holdings
Meta Platforms, Inc., "A" 11.7%
Alphabet, Inc., "A" 7.6%
Microsoft Corp. 7.0%
Apple, Inc. 6.3%
NVIDIA Corp. 4.4%
Broadcom, Inc. 3.5%
Salesforce, Inc. 3.4%
Oracle Corp. 3.3%
Accenture PLC, "A" 2.7%
ServiceNow, Inc. 2.7%
Top five industries
Computer Software 32.7%
Interactive Media Services 20.6%
Computer Software - Systems 18.3%
Electronics 16.4%
Business Services 6.0%
For purposes of these classifications, MFS uses its own internal sector/industry classification methodology, which may deviate from classification methodologies used by other industry participants (e.g., the Global Industry Classification Standard).
Largest Holdings [Text Block]
Top ten holdings
Meta Platforms, Inc., "A" 11.7%
Alphabet, Inc., "A" 7.6%
Microsoft Corp. 7.0%
Apple, Inc. 6.3%
NVIDIA Corp. 4.4%
Broadcom, Inc. 3.5%
Salesforce, Inc. 3.4%
Oracle Corp. 3.3%
Accenture PLC, "A" 2.7%
ServiceNow, Inc. 2.7%
C000002251 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Technology Fund
Class Name Class B
Trading Symbol MTCBX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Technology Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
B $96 1.86%
Expenses Paid, Amount $ 96
Expense Ratio, Percent 1.86%
Net Assets $ 2,053,482,986
Holdings Count | Holding 57
Investment Company Portfolio Turnover 26.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 2,053,482,986 Portfolio Turnover Rate (%): 26
Total Number of Holdings: 57
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 98.7%
Money Market Funds 1.3%
Top ten holdings
Meta Platforms, Inc., "A" 11.7%
Alphabet, Inc., "A" 7.6%
Microsoft Corp. 7.0%
Apple, Inc. 6.3%
NVIDIA Corp. 4.4%
Broadcom, Inc. 3.5%
Salesforce, Inc. 3.4%
Oracle Corp. 3.3%
Accenture PLC, "A" 2.7%
ServiceNow, Inc. 2.7%
Top five industries
Computer Software 32.7%
Interactive Media Services 20.6%
Computer Software - Systems 18.3%
Electronics 16.4%
Business Services 6.0%
For purposes of these classifications, MFS uses its own internal sector/industry classification methodology, which may deviate from classification methodologies used by other industry participants (e.g., the Global Industry Classification Standard).
Largest Holdings [Text Block]
Top ten holdings
Meta Platforms, Inc., "A" 11.7%
Alphabet, Inc., "A" 7.6%
Microsoft Corp. 7.0%
Apple, Inc. 6.3%
NVIDIA Corp. 4.4%
Broadcom, Inc. 3.5%
Salesforce, Inc. 3.4%
Oracle Corp. 3.3%
Accenture PLC, "A" 2.7%
ServiceNow, Inc. 2.7%
C000002252 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Technology Fund
Class Name Class C
Trading Symbol MTCCX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Technology Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
C $96 1.86%
Expenses Paid, Amount $ 96
Expense Ratio, Percent 1.86%
Net Assets $ 2,053,482,986
Holdings Count | Holding 57
Investment Company Portfolio Turnover 26.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 2,053,482,986 Portfolio Turnover Rate (%): 26
Total Number of Holdings: 57
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 98.7%
Money Market Funds 1.3%
Top ten holdings
Meta Platforms, Inc., "A" 11.7%
Alphabet, Inc., "A" 7.6%
Microsoft Corp. 7.0%
Apple, Inc. 6.3%
NVIDIA Corp. 4.4%
Broadcom, Inc. 3.5%
Salesforce, Inc. 3.4%
Oracle Corp. 3.3%
Accenture PLC, "A" 2.7%
ServiceNow, Inc. 2.7%
Top five industries
Computer Software 32.7%
Interactive Media Services 20.6%
Computer Software - Systems 18.3%
Electronics 16.4%
Business Services 6.0%
For purposes of these classifications, MFS uses its own internal sector/industry classification methodology, which may deviate from classification methodologies used by other industry participants (e.g., the Global Industry Classification Standard).
Largest Holdings [Text Block]
Top ten holdings
Meta Platforms, Inc., "A" 11.7%
Alphabet, Inc., "A" 7.6%
Microsoft Corp. 7.0%
Apple, Inc. 6.3%
NVIDIA Corp. 4.4%
Broadcom, Inc. 3.5%
Salesforce, Inc. 3.4%
Oracle Corp. 3.3%
Accenture PLC, "A" 2.7%
ServiceNow, Inc. 2.7%
C000002253 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Technology Fund
Class Name Class I
Trading Symbol MTCIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Technology Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
I $44 0.85%
Expenses Paid, Amount $ 44
Expense Ratio, Percent 0.85%
Net Assets $ 2,053,482,986
Holdings Count | Holding 57
Investment Company Portfolio Turnover 26.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 2,053,482,986 Portfolio Turnover Rate (%): 26
Total Number of Holdings: 57
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 98.7%
Money Market Funds 1.3%
Top ten holdings
Meta Platforms, Inc., "A" 11.7%
Alphabet, Inc., "A" 7.6%
Microsoft Corp. 7.0%
Apple, Inc. 6.3%
NVIDIA Corp. 4.4%
Broadcom, Inc. 3.5%
Salesforce, Inc. 3.4%
Oracle Corp. 3.3%
Accenture PLC, "A" 2.7%
ServiceNow, Inc. 2.7%
Top five industries
Computer Software 32.7%
Interactive Media Services 20.6%
Computer Software - Systems 18.3%
Electronics 16.4%
Business Services 6.0%
For purposes of these classifications, MFS uses its own internal sector/industry classification methodology, which may deviate from classification methodologies used by other industry participants (e.g., the Global Industry Classification Standard).
Largest Holdings [Text Block]
Top ten holdings
Meta Platforms, Inc., "A" 11.7%
Alphabet, Inc., "A" 7.6%
Microsoft Corp. 7.0%
Apple, Inc. 6.3%
NVIDIA Corp. 4.4%
Broadcom, Inc. 3.5%
Salesforce, Inc. 3.4%
Oracle Corp. 3.3%
Accenture PLC, "A" 2.7%
ServiceNow, Inc. 2.7%
C000002255 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Technology Fund
Class Name Class R1
Trading Symbol MTCKX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Technology Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R1 $96 1.86%
Expenses Paid, Amount $ 96
Expense Ratio, Percent 1.86%
Net Assets $ 2,053,482,986
Holdings Count | Holding 57
Investment Company Portfolio Turnover 26.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 2,053,482,986 Portfolio Turnover Rate (%): 26
Total Number of Holdings: 57
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 98.7%
Money Market Funds 1.3%
Top ten holdings
Meta Platforms, Inc., "A" 11.7%
Alphabet, Inc., "A" 7.6%
Microsoft Corp. 7.0%
Apple, Inc. 6.3%
NVIDIA Corp. 4.4%
Broadcom, Inc. 3.5%
Salesforce, Inc. 3.4%
Oracle Corp. 3.3%
Accenture PLC, "A" 2.7%
ServiceNow, Inc. 2.7%
Top five industries
Computer Software 32.7%
Interactive Media Services 20.6%
Computer Software - Systems 18.3%
Electronics 16.4%
Business Services 6.0%
For purposes of these classifications, MFS uses its own internal sector/industry classification methodology, which may deviate from classification methodologies used by other industry participants (e.g., the Global Industry Classification Standard).
Largest Holdings [Text Block]
Top ten holdings
Meta Platforms, Inc., "A" 11.7%
Alphabet, Inc., "A" 7.6%
Microsoft Corp. 7.0%
Apple, Inc. 6.3%
NVIDIA Corp. 4.4%
Broadcom, Inc. 3.5%
Salesforce, Inc. 3.4%
Oracle Corp. 3.3%
Accenture PLC, "A" 2.7%
ServiceNow, Inc. 2.7%
C000002257 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Technology Fund
Class Name Class R2
Trading Symbol MTERX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Technology Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R2 $70 1.35%
Expenses Paid, Amount $ 70
Expense Ratio, Percent 1.35%
Net Assets $ 2,053,482,986
Holdings Count | Holding 57
Investment Company Portfolio Turnover 26.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 2,053,482,986 Portfolio Turnover Rate (%): 26
Total Number of Holdings: 57
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 98.7%
Money Market Funds 1.3%
Top ten holdings
Meta Platforms, Inc., "A" 11.7%
Alphabet, Inc., "A" 7.6%
Microsoft Corp. 7.0%
Apple, Inc. 6.3%
NVIDIA Corp. 4.4%
Broadcom, Inc. 3.5%
Salesforce, Inc. 3.4%
Oracle Corp. 3.3%
Accenture PLC, "A" 2.7%
ServiceNow, Inc. 2.7%
Top five industries
Computer Software 32.7%
Interactive Media Services 20.6%
Computer Software - Systems 18.3%
Electronics 16.4%
Business Services 6.0%
For purposes of these classifications, MFS uses its own internal sector/industry classification methodology, which may deviate from classification methodologies used by other industry participants (e.g., the Global Industry Classification Standard).
Largest Holdings [Text Block]
Top ten holdings
Meta Platforms, Inc., "A" 11.7%
Alphabet, Inc., "A" 7.6%
Microsoft Corp. 7.0%
Apple, Inc. 6.3%
NVIDIA Corp. 4.4%
Broadcom, Inc. 3.5%
Salesforce, Inc. 3.4%
Oracle Corp. 3.3%
Accenture PLC, "A" 2.7%
ServiceNow, Inc. 2.7%
C000002258 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Technology Fund
Class Name Class R3
Trading Symbol MTCHX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Technology Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R3 $57 1.10%
Expenses Paid, Amount $ 57
Expense Ratio, Percent 1.10%
Net Assets $ 2,053,482,986
Holdings Count | Holding 57
Investment Company Portfolio Turnover 26.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 2,053,482,986 Portfolio Turnover Rate (%): 26
Total Number of Holdings: 57
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 98.7%
Money Market Funds 1.3%
Top ten holdings
Meta Platforms, Inc., "A" 11.7%
Alphabet, Inc., "A" 7.6%
Microsoft Corp. 7.0%
Apple, Inc. 6.3%
NVIDIA Corp. 4.4%
Broadcom, Inc. 3.5%
Salesforce, Inc. 3.4%
Oracle Corp. 3.3%
Accenture PLC, "A" 2.7%
ServiceNow, Inc. 2.7%
Top five industries
Computer Software 32.7%
Interactive Media Services 20.6%
Computer Software - Systems 18.3%
Electronics 16.4%
Business Services 6.0%
For purposes of these classifications, MFS uses its own internal sector/industry classification methodology, which may deviate from classification methodologies used by other industry participants (e.g., the Global Industry Classification Standard).
Largest Holdings [Text Block]
Top ten holdings
Meta Platforms, Inc., "A" 11.7%
Alphabet, Inc., "A" 7.6%
Microsoft Corp. 7.0%
Apple, Inc. 6.3%
NVIDIA Corp. 4.4%
Broadcom, Inc. 3.5%
Salesforce, Inc. 3.4%
Oracle Corp. 3.3%
Accenture PLC, "A" 2.7%
ServiceNow, Inc. 2.7%
C000002250 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Technology Fund
Class Name Class R4
Trading Symbol MTCJX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Technology Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R4 $44 0.85%
Expenses Paid, Amount $ 44
Expense Ratio, Percent 0.85%
Net Assets $ 2,053,482,986
Holdings Count | Holding 57
Investment Company Portfolio Turnover 26.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 2,053,482,986 Portfolio Turnover Rate (%): 26
Total Number of Holdings: 57
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 98.7%
Money Market Funds 1.3%
Top ten holdings
Meta Platforms, Inc., "A" 11.7%
Alphabet, Inc., "A" 7.6%
Microsoft Corp. 7.0%
Apple, Inc. 6.3%
NVIDIA Corp. 4.4%
Broadcom, Inc. 3.5%
Salesforce, Inc. 3.4%
Oracle Corp. 3.3%
Accenture PLC, "A" 2.7%
ServiceNow, Inc. 2.7%
Top five industries
Computer Software 32.7%
Interactive Media Services 20.6%
Computer Software - Systems 18.3%
Electronics 16.4%
Business Services 6.0%
For purposes of these classifications, MFS uses its own internal sector/industry classification methodology, which may deviate from classification methodologies used by other industry participants (e.g., the Global Industry Classification Standard).
Largest Holdings [Text Block]
Top ten holdings
Meta Platforms, Inc., "A" 11.7%
Alphabet, Inc., "A" 7.6%
Microsoft Corp. 7.0%
Apple, Inc. 6.3%
NVIDIA Corp. 4.4%
Broadcom, Inc. 3.5%
Salesforce, Inc. 3.4%
Oracle Corp. 3.3%
Accenture PLC, "A" 2.7%
ServiceNow, Inc. 2.7%
C000124425 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Technology Fund
Class Name Class R6
Trading Symbol MTCLX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Technology Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R6 $40 0.77%
Expenses Paid, Amount $ 40
Expense Ratio, Percent 0.77%
Net Assets $ 2,053,482,986
Holdings Count | Holding 57
Investment Company Portfolio Turnover 26.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 2,053,482,986 Portfolio Turnover Rate (%): 26
Total Number of Holdings: 57
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 98.7%
Money Market Funds 1.3%
Top ten holdings
Meta Platforms, Inc., "A" 11.7%
Alphabet, Inc., "A" 7.6%
Microsoft Corp. 7.0%
Apple, Inc. 6.3%
NVIDIA Corp. 4.4%
Broadcom, Inc. 3.5%
Salesforce, Inc. 3.4%
Oracle Corp. 3.3%
Accenture PLC, "A" 2.7%
ServiceNow, Inc. 2.7%
Top five industries
Computer Software 32.7%
Interactive Media Services 20.6%
Computer Software - Systems 18.3%
Electronics 16.4%
Business Services 6.0%
For purposes of these classifications, MFS uses its own internal sector/industry classification methodology, which may deviate from classification methodologies used by other industry participants (e.g., the Global Industry Classification Standard).
Largest Holdings [Text Block]
Top ten holdings
Meta Platforms, Inc., "A" 11.7%
Alphabet, Inc., "A" 7.6%
Microsoft Corp. 7.0%
Apple, Inc. 6.3%
NVIDIA Corp. 4.4%
Broadcom, Inc. 3.5%
Salesforce, Inc. 3.4%
Oracle Corp. 3.3%
Accenture PLC, "A" 2.7%
ServiceNow, Inc. 2.7%
C000002259 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Value Fund
Class Name Class A
Trading Symbol MEIAX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Value Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
A $40 0.79%
Expenses Paid, Amount $ 40
Expense Ratio, Percent 0.79%
Net Assets $ 58,675,023,168
Holdings Count | Holding 72
Investment Company Portfolio Turnover 6.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 58,675,023,168 Portfolio Turnover Rate (%): 6
Total Number of Holdings: 72
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 99.0%
Money Market Funds 1.0%
Equity sectors
Financials 29.9%
Industrials 15.9%
Health Care 15.1%
Utilities 8.9%
Consumer Staples 7.7%
Information Technology 7.4%
Energy 6.2%
Consumer Discretionary 3.4%
Materials 2.5%
Real Estate 2.0%
Top ten holdings
Progressive Corp. 4.4%
JPMorgan Chase & Co. 4.3%
Cigna Group 3.0%
McKesson Corp. 2.9%
Marsh & McLennan Cos., Inc. 2.5%
Aon PLC 2.3%
American Express Co. 2.3%
Morgan Stanley 2.3%
RTX Corp. 2.2%
Johnson & Johnson 2.2%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
Progressive Corp. 4.4%
JPMorgan Chase & Co. 4.3%
Cigna Group 3.0%
McKesson Corp. 2.9%
Marsh & McLennan Cos., Inc. 2.5%
Aon PLC 2.3%
American Express Co. 2.3%
Morgan Stanley 2.3%
RTX Corp. 2.2%
Johnson & Johnson 2.2%
C000002264 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Value Fund
Class Name Class B
Trading Symbol MFEBX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Value Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
B $77 1.54%
Expenses Paid, Amount $ 77
Expense Ratio, Percent 1.54%
Net Assets $ 58,675,023,168
Holdings Count | Holding 72
Investment Company Portfolio Turnover 6.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 58,675,023,168 Portfolio Turnover Rate (%): 6
Total Number of Holdings: 72
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 99.0%
Money Market Funds 1.0%
Equity sectors
Financials 29.9%
Industrials 15.9%
Health Care 15.1%
Utilities 8.9%
Consumer Staples 7.7%
Information Technology 7.4%
Energy 6.2%
Consumer Discretionary 3.4%
Materials 2.5%
Real Estate 2.0%
Top ten holdings
Progressive Corp. 4.4%
JPMorgan Chase & Co. 4.3%
Cigna Group 3.0%
McKesson Corp. 2.9%
Marsh & McLennan Cos., Inc. 2.5%
Aon PLC 2.3%
American Express Co. 2.3%
Morgan Stanley 2.3%
RTX Corp. 2.2%
Johnson & Johnson 2.2%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
Progressive Corp. 4.4%
JPMorgan Chase & Co. 4.3%
Cigna Group 3.0%
McKesson Corp. 2.9%
Marsh & McLennan Cos., Inc. 2.5%
Aon PLC 2.3%
American Express Co. 2.3%
Morgan Stanley 2.3%
RTX Corp. 2.2%
Johnson & Johnson 2.2%
C000002265 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Value Fund
Class Name Class C
Trading Symbol MEICX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Value Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
C $77 1.54%
Expenses Paid, Amount $ 77
Expense Ratio, Percent 1.54%
Net Assets $ 58,675,023,168
Holdings Count | Holding 72
Investment Company Portfolio Turnover 6.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 58,675,023,168 Portfolio Turnover Rate (%): 6
Total Number of Holdings: 72
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 99.0%
Money Market Funds 1.0%
Equity sectors
Financials 29.9%
Industrials 15.9%
Health Care 15.1%
Utilities 8.9%
Consumer Staples 7.7%
Information Technology 7.4%
Energy 6.2%
Consumer Discretionary 3.4%
Materials 2.5%
Real Estate 2.0%
Top ten holdings
Progressive Corp. 4.4%
JPMorgan Chase & Co. 4.3%
Cigna Group 3.0%
McKesson Corp. 2.9%
Marsh & McLennan Cos., Inc. 2.5%
Aon PLC 2.3%
American Express Co. 2.3%
Morgan Stanley 2.3%
RTX Corp. 2.2%
Johnson & Johnson 2.2%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
Progressive Corp. 4.4%
JPMorgan Chase & Co. 4.3%
Cigna Group 3.0%
McKesson Corp. 2.9%
Marsh & McLennan Cos., Inc. 2.5%
Aon PLC 2.3%
American Express Co. 2.3%
Morgan Stanley 2.3%
RTX Corp. 2.2%
Johnson & Johnson 2.2%
C000002266 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Value Fund
Class Name Class I
Trading Symbol MEIIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Value Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
I $27 0.54%
Expenses Paid, Amount $ 27
Expense Ratio, Percent 0.54%
Net Assets $ 58,675,023,168
Holdings Count | Holding 72
Investment Company Portfolio Turnover 6.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 58,675,023,168 Portfolio Turnover Rate (%): 6
Total Number of Holdings: 72
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 99.0%
Money Market Funds 1.0%
Equity sectors
Financials 29.9%
Industrials 15.9%
Health Care 15.1%
Utilities 8.9%
Consumer Staples 7.7%
Information Technology 7.4%
Energy 6.2%
Consumer Discretionary 3.4%
Materials 2.5%
Real Estate 2.0%
Top ten holdings
Progressive Corp. 4.4%
JPMorgan Chase & Co. 4.3%
Cigna Group 3.0%
McKesson Corp. 2.9%
Marsh & McLennan Cos., Inc. 2.5%
Aon PLC 2.3%
American Express Co. 2.3%
Morgan Stanley 2.3%
RTX Corp. 2.2%
Johnson & Johnson 2.2%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
Progressive Corp. 4.4%
JPMorgan Chase & Co. 4.3%
Cigna Group 3.0%
McKesson Corp. 2.9%
Marsh & McLennan Cos., Inc. 2.5%
Aon PLC 2.3%
American Express Co. 2.3%
Morgan Stanley 2.3%
RTX Corp. 2.2%
Johnson & Johnson 2.2%
C000002268 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Value Fund
Class Name Class R1
Trading Symbol MEIGX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Value Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R1 $77 1.54%
Expenses Paid, Amount $ 77
Expense Ratio, Percent 1.54%
Net Assets $ 58,675,023,168
Holdings Count | Holding 72
Investment Company Portfolio Turnover 6.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 58,675,023,168 Portfolio Turnover Rate (%): 6
Total Number of Holdings: 72
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 99.0%
Money Market Funds 1.0%
Equity sectors
Financials 29.9%
Industrials 15.9%
Health Care 15.1%
Utilities 8.9%
Consumer Staples 7.7%
Information Technology 7.4%
Energy 6.2%
Consumer Discretionary 3.4%
Materials 2.5%
Real Estate 2.0%
Top ten holdings
Progressive Corp. 4.4%
JPMorgan Chase & Co. 4.3%
Cigna Group 3.0%
McKesson Corp. 2.9%
Marsh & McLennan Cos., Inc. 2.5%
Aon PLC 2.3%
American Express Co. 2.3%
Morgan Stanley 2.3%
RTX Corp. 2.2%
Johnson & Johnson 2.2%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
Progressive Corp. 4.4%
JPMorgan Chase & Co. 4.3%
Cigna Group 3.0%
McKesson Corp. 2.9%
Marsh & McLennan Cos., Inc. 2.5%
Aon PLC 2.3%
American Express Co. 2.3%
Morgan Stanley 2.3%
RTX Corp. 2.2%
Johnson & Johnson 2.2%
C000002270 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Value Fund
Class Name Class R2
Trading Symbol MVRRX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Value Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R2 $52 1.04%
Expenses Paid, Amount $ 52
Expense Ratio, Percent 1.04%
Net Assets $ 58,675,023,168
Holdings Count | Holding 72
Investment Company Portfolio Turnover 6.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 58,675,023,168 Portfolio Turnover Rate (%): 6
Total Number of Holdings: 72
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 99.0%
Money Market Funds 1.0%
Equity sectors
Financials 29.9%
Industrials 15.9%
Health Care 15.1%
Utilities 8.9%
Consumer Staples 7.7%
Information Technology 7.4%
Energy 6.2%
Consumer Discretionary 3.4%
Materials 2.5%
Real Estate 2.0%
Top ten holdings
Progressive Corp. 4.4%
JPMorgan Chase & Co. 4.3%
Cigna Group 3.0%
McKesson Corp. 2.9%
Marsh & McLennan Cos., Inc. 2.5%
Aon PLC 2.3%
American Express Co. 2.3%
Morgan Stanley 2.3%
RTX Corp. 2.2%
Johnson & Johnson 2.2%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
Progressive Corp. 4.4%
JPMorgan Chase & Co. 4.3%
Cigna Group 3.0%
McKesson Corp. 2.9%
Marsh & McLennan Cos., Inc. 2.5%
Aon PLC 2.3%
American Express Co. 2.3%
Morgan Stanley 2.3%
RTX Corp. 2.2%
Johnson & Johnson 2.2%
C000002271 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Value Fund
Class Name Class R3
Trading Symbol MEIHX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Value Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R3 $40 0.79%
Expenses Paid, Amount $ 40
Expense Ratio, Percent 0.79%
Net Assets $ 58,675,023,168
Holdings Count | Holding 72
Investment Company Portfolio Turnover 6.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 58,675,023,168 Portfolio Turnover Rate (%): 6
Total Number of Holdings: 72
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 99.0%
Money Market Funds 1.0%
Equity sectors
Financials 29.9%
Industrials 15.9%
Health Care 15.1%
Utilities 8.9%
Consumer Staples 7.7%
Information Technology 7.4%
Energy 6.2%
Consumer Discretionary 3.4%
Materials 2.5%
Real Estate 2.0%
Top ten holdings
Progressive Corp. 4.4%
JPMorgan Chase & Co. 4.3%
Cigna Group 3.0%
McKesson Corp. 2.9%
Marsh & McLennan Cos., Inc. 2.5%
Aon PLC 2.3%
American Express Co. 2.3%
Morgan Stanley 2.3%
RTX Corp. 2.2%
Johnson & Johnson 2.2%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
Progressive Corp. 4.4%
JPMorgan Chase & Co. 4.3%
Cigna Group 3.0%
McKesson Corp. 2.9%
Marsh & McLennan Cos., Inc. 2.5%
Aon PLC 2.3%
American Express Co. 2.3%
Morgan Stanley 2.3%
RTX Corp. 2.2%
Johnson & Johnson 2.2%
C000002260 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Value Fund
Class Name Class R4
Trading Symbol MEIJX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Value Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R4 $27 0.54%
Expenses Paid, Amount $ 27
Expense Ratio, Percent 0.54%
Net Assets $ 58,675,023,168
Holdings Count | Holding 72
Investment Company Portfolio Turnover 6.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 58,675,023,168 Portfolio Turnover Rate (%): 6
Total Number of Holdings: 72
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 99.0%
Money Market Funds 1.0%
Equity sectors
Financials 29.9%
Industrials 15.9%
Health Care 15.1%
Utilities 8.9%
Consumer Staples 7.7%
Information Technology 7.4%
Energy 6.2%
Consumer Discretionary 3.4%
Materials 2.5%
Real Estate 2.0%
Top ten holdings
Progressive Corp. 4.4%
JPMorgan Chase & Co. 4.3%
Cigna Group 3.0%
McKesson Corp. 2.9%
Marsh & McLennan Cos., Inc. 2.5%
Aon PLC 2.3%
American Express Co. 2.3%
Morgan Stanley 2.3%
RTX Corp. 2.2%
Johnson & Johnson 2.2%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
Progressive Corp. 4.4%
JPMorgan Chase & Co. 4.3%
Cigna Group 3.0%
McKesson Corp. 2.9%
Marsh & McLennan Cos., Inc. 2.5%
Aon PLC 2.3%
American Express Co. 2.3%
Morgan Stanley 2.3%
RTX Corp. 2.2%
Johnson & Johnson 2.2%
C000033014 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Value Fund
Class Name Class R6
Trading Symbol MEIKX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Value Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R6 $22 0.43%
Expenses Paid, Amount $ 22
Expense Ratio, Percent 0.43%
Net Assets $ 58,675,023,168
Holdings Count | Holding 72
Investment Company Portfolio Turnover 6.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 58,675,023,168 Portfolio Turnover Rate (%): 6
Total Number of Holdings: 72
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 99.0%
Money Market Funds 1.0%
Equity sectors
Financials 29.9%
Industrials 15.9%
Health Care 15.1%
Utilities 8.9%
Consumer Staples 7.7%
Information Technology 7.4%
Energy 6.2%
Consumer Discretionary 3.4%
Materials 2.5%
Real Estate 2.0%
Top ten holdings
Progressive Corp. 4.4%
JPMorgan Chase & Co. 4.3%
Cigna Group 3.0%
McKesson Corp. 2.9%
Marsh & McLennan Cos., Inc. 2.5%
Aon PLC 2.3%
American Express Co. 2.3%
Morgan Stanley 2.3%
RTX Corp. 2.2%
Johnson & Johnson 2.2%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
Progressive Corp. 4.4%
JPMorgan Chase & Co. 4.3%
Cigna Group 3.0%
McKesson Corp. 2.9%
Marsh & McLennan Cos., Inc. 2.5%
Aon PLC 2.3%
American Express Co. 2.3%
Morgan Stanley 2.3%
RTX Corp. 2.2%
Johnson & Johnson 2.2%
C000132013 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Low Volatility Equity Fund
Class Name Class A
Trading Symbol MLVAX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Low Volatility Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
A $45 0.90%
Expenses Paid, Amount $ 45
Expense Ratio, Percent 0.90%
Net Assets $ 392,353,011
Holdings Count | Holding 106
Investment Company Portfolio Turnover 11.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 392,353,011 Portfolio Turnover Rate (%): 11
Total Number of Holdings: 106
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 99.8%
Money Market Funds 0.2%
Equity sectors
Information Technology 23.3%
Health Care 15.4%
Financials 14.2%
Industrials 11.4%
Consumer Staples 10.6%
Consumer Discretionary 6.4%
Utilities 5.3%
Real Estate 5.3%
Communication Services 4.3%
Materials 2.4%
Energy 1.2%
Top ten holdings
McKesson Corp. 3.1%
Johnson & Johnson 3.0%
Motorola Solutions, Inc. 2.7%
TE Connectivity PLC 2.6%
Teledyne Technologies, Inc. 2.5%
Amphenol Corp., "A" 2.4%
General Mills, Inc. 2.4%
Visa, Inc., "A" 2.3%
Cognizant Technology Solutions Corp., "A" 2.3%
Accenture PLC, "A" 2.2%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
McKesson Corp. 3.1%
Johnson & Johnson 3.0%
Motorola Solutions, Inc. 2.7%
TE Connectivity PLC 2.6%
Teledyne Technologies, Inc. 2.5%
Amphenol Corp., "A" 2.4%
General Mills, Inc. 2.4%
Visa, Inc., "A" 2.3%
Cognizant Technology Solutions Corp., "A" 2.3%
Accenture PLC, "A" 2.2%
C000132014 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Low Volatility Equity Fund
Class Name Class B
Trading Symbol MLVBX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Low Volatility Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
B $82 1.65%
Expenses Paid, Amount $ 82
Expense Ratio, Percent 1.65%
Net Assets $ 392,353,011
Holdings Count | Holding 106
Investment Company Portfolio Turnover 11.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 392,353,011 Portfolio Turnover Rate (%): 11
Total Number of Holdings: 106
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 99.8%
Money Market Funds 0.2%
Equity sectors
Information Technology 23.3%
Health Care 15.4%
Financials 14.2%
Industrials 11.4%
Consumer Staples 10.6%
Consumer Discretionary 6.4%
Utilities 5.3%
Real Estate 5.3%
Communication Services 4.3%
Materials 2.4%
Energy 1.2%
Top ten holdings
McKesson Corp. 3.1%
Johnson & Johnson 3.0%
Motorola Solutions, Inc. 2.7%
TE Connectivity PLC 2.6%
Teledyne Technologies, Inc. 2.5%
Amphenol Corp., "A" 2.4%
General Mills, Inc. 2.4%
Visa, Inc., "A" 2.3%
Cognizant Technology Solutions Corp., "A" 2.3%
Accenture PLC, "A" 2.2%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
McKesson Corp. 3.1%
Johnson & Johnson 3.0%
Motorola Solutions, Inc. 2.7%
TE Connectivity PLC 2.6%
Teledyne Technologies, Inc. 2.5%
Amphenol Corp., "A" 2.4%
General Mills, Inc. 2.4%
Visa, Inc., "A" 2.3%
Cognizant Technology Solutions Corp., "A" 2.3%
Accenture PLC, "A" 2.2%
C000132015 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Low Volatility Equity Fund
Class Name Class C
Trading Symbol MLVGX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Low Volatility Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
C $82 1.65%
Expenses Paid, Amount $ 82
Expense Ratio, Percent 1.65%
Net Assets $ 392,353,011
Holdings Count | Holding 106
Investment Company Portfolio Turnover 11.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 392,353,011 Portfolio Turnover Rate (%): 11
Total Number of Holdings: 106
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 99.8%
Money Market Funds 0.2%
Equity sectors
Information Technology 23.3%
Health Care 15.4%
Financials 14.2%
Industrials 11.4%
Consumer Staples 10.6%
Consumer Discretionary 6.4%
Utilities 5.3%
Real Estate 5.3%
Communication Services 4.3%
Materials 2.4%
Energy 1.2%
Top ten holdings
McKesson Corp. 3.1%
Johnson & Johnson 3.0%
Motorola Solutions, Inc. 2.7%
TE Connectivity PLC 2.6%
Teledyne Technologies, Inc. 2.5%
Amphenol Corp., "A" 2.4%
General Mills, Inc. 2.4%
Visa, Inc., "A" 2.3%
Cognizant Technology Solutions Corp., "A" 2.3%
Accenture PLC, "A" 2.2%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
McKesson Corp. 3.1%
Johnson & Johnson 3.0%
Motorola Solutions, Inc. 2.7%
TE Connectivity PLC 2.6%
Teledyne Technologies, Inc. 2.5%
Amphenol Corp., "A" 2.4%
General Mills, Inc. 2.4%
Visa, Inc., "A" 2.3%
Cognizant Technology Solutions Corp., "A" 2.3%
Accenture PLC, "A" 2.2%
C000132016 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Low Volatility Equity Fund
Class Name Class I
Trading Symbol MLVHX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Low Volatility Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
I $32 0.65%
Expenses Paid, Amount $ 32
Expense Ratio, Percent 0.65%
Net Assets $ 392,353,011
Holdings Count | Holding 106
Investment Company Portfolio Turnover 11.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 392,353,011 Portfolio Turnover Rate (%): 11
Total Number of Holdings: 106
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 99.8%
Money Market Funds 0.2%
Equity sectors
Information Technology 23.3%
Health Care 15.4%
Financials 14.2%
Industrials 11.4%
Consumer Staples 10.6%
Consumer Discretionary 6.4%
Utilities 5.3%
Real Estate 5.3%
Communication Services 4.3%
Materials 2.4%
Energy 1.2%
Top ten holdings
McKesson Corp. 3.1%
Johnson & Johnson 3.0%
Motorola Solutions, Inc. 2.7%
TE Connectivity PLC 2.6%
Teledyne Technologies, Inc. 2.5%
Amphenol Corp., "A" 2.4%
General Mills, Inc. 2.4%
Visa, Inc., "A" 2.3%
Cognizant Technology Solutions Corp., "A" 2.3%
Accenture PLC, "A" 2.2%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
McKesson Corp. 3.1%
Johnson & Johnson 3.0%
Motorola Solutions, Inc. 2.7%
TE Connectivity PLC 2.6%
Teledyne Technologies, Inc. 2.5%
Amphenol Corp., "A" 2.4%
General Mills, Inc. 2.4%
Visa, Inc., "A" 2.3%
Cognizant Technology Solutions Corp., "A" 2.3%
Accenture PLC, "A" 2.2%
C000132017 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Low Volatility Equity Fund
Class Name Class R1
Trading Symbol MLVMX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Low Volatility Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R1 $82 1.65%
Expenses Paid, Amount $ 82
Expense Ratio, Percent 1.65%
Net Assets $ 392,353,011
Holdings Count | Holding 106
Investment Company Portfolio Turnover 11.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 392,353,011 Portfolio Turnover Rate (%): 11
Total Number of Holdings: 106
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 99.8%
Money Market Funds 0.2%
Equity sectors
Information Technology 23.3%
Health Care 15.4%
Financials 14.2%
Industrials 11.4%
Consumer Staples 10.6%
Consumer Discretionary 6.4%
Utilities 5.3%
Real Estate 5.3%
Communication Services 4.3%
Materials 2.4%
Energy 1.2%
Top ten holdings
McKesson Corp. 3.1%
Johnson & Johnson 3.0%
Motorola Solutions, Inc. 2.7%
TE Connectivity PLC 2.6%
Teledyne Technologies, Inc. 2.5%
Amphenol Corp., "A" 2.4%
General Mills, Inc. 2.4%
Visa, Inc., "A" 2.3%
Cognizant Technology Solutions Corp., "A" 2.3%
Accenture PLC, "A" 2.2%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
McKesson Corp. 3.1%
Johnson & Johnson 3.0%
Motorola Solutions, Inc. 2.7%
TE Connectivity PLC 2.6%
Teledyne Technologies, Inc. 2.5%
Amphenol Corp., "A" 2.4%
General Mills, Inc. 2.4%
Visa, Inc., "A" 2.3%
Cognizant Technology Solutions Corp., "A" 2.3%
Accenture PLC, "A" 2.2%
C000132018 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Low Volatility Equity Fund
Class Name Class R2
Trading Symbol MLVOX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Low Volatility Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R2 $57 1.15%
Expenses Paid, Amount $ 57
Expense Ratio, Percent 1.15%
Net Assets $ 392,353,011
Holdings Count | Holding 106
Investment Company Portfolio Turnover 11.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 392,353,011 Portfolio Turnover Rate (%): 11
Total Number of Holdings: 106
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 99.8%
Money Market Funds 0.2%
Equity sectors
Information Technology 23.3%
Health Care 15.4%
Financials 14.2%
Industrials 11.4%
Consumer Staples 10.6%
Consumer Discretionary 6.4%
Utilities 5.3%
Real Estate 5.3%
Communication Services 4.3%
Materials 2.4%
Energy 1.2%
Top ten holdings
McKesson Corp. 3.1%
Johnson & Johnson 3.0%
Motorola Solutions, Inc. 2.7%
TE Connectivity PLC 2.6%
Teledyne Technologies, Inc. 2.5%
Amphenol Corp., "A" 2.4%
General Mills, Inc. 2.4%
Visa, Inc., "A" 2.3%
Cognizant Technology Solutions Corp., "A" 2.3%
Accenture PLC, "A" 2.2%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
McKesson Corp. 3.1%
Johnson & Johnson 3.0%
Motorola Solutions, Inc. 2.7%
TE Connectivity PLC 2.6%
Teledyne Technologies, Inc. 2.5%
Amphenol Corp., "A" 2.4%
General Mills, Inc. 2.4%
Visa, Inc., "A" 2.3%
Cognizant Technology Solutions Corp., "A" 2.3%
Accenture PLC, "A" 2.2%
C000132019 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Low Volatility Equity Fund
Class Name Class R3
Trading Symbol MLVPX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Low Volatility Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R3 $45 0.90%
Expenses Paid, Amount $ 45
Expense Ratio, Percent 0.90%
Net Assets $ 392,353,011
Holdings Count | Holding 106
Investment Company Portfolio Turnover 11.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 392,353,011 Portfolio Turnover Rate (%): 11
Total Number of Holdings: 106
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 99.8%
Money Market Funds 0.2%
Equity sectors
Information Technology 23.3%
Health Care 15.4%
Financials 14.2%
Industrials 11.4%
Consumer Staples 10.6%
Consumer Discretionary 6.4%
Utilities 5.3%
Real Estate 5.3%
Communication Services 4.3%
Materials 2.4%
Energy 1.2%
Top ten holdings
McKesson Corp. 3.1%
Johnson & Johnson 3.0%
Motorola Solutions, Inc. 2.7%
TE Connectivity PLC 2.6%
Teledyne Technologies, Inc. 2.5%
Amphenol Corp., "A" 2.4%
General Mills, Inc. 2.4%
Visa, Inc., "A" 2.3%
Cognizant Technology Solutions Corp., "A" 2.3%
Accenture PLC, "A" 2.2%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
McKesson Corp. 3.1%
Johnson & Johnson 3.0%
Motorola Solutions, Inc. 2.7%
TE Connectivity PLC 2.6%
Teledyne Technologies, Inc. 2.5%
Amphenol Corp., "A" 2.4%
General Mills, Inc. 2.4%
Visa, Inc., "A" 2.3%
Cognizant Technology Solutions Corp., "A" 2.3%
Accenture PLC, "A" 2.2%
C000132020 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Low Volatility Equity Fund
Class Name Class R4
Trading Symbol MLVRX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Low Volatility Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R4 $32 0.65%
Expenses Paid, Amount $ 32
Expense Ratio, Percent 0.65%
Net Assets $ 392,353,011
Holdings Count | Holding 106
Investment Company Portfolio Turnover 11.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 392,353,011 Portfolio Turnover Rate (%): 11
Total Number of Holdings: 106
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 99.8%
Money Market Funds 0.2%
Equity sectors
Information Technology 23.3%
Health Care 15.4%
Financials 14.2%
Industrials 11.4%
Consumer Staples 10.6%
Consumer Discretionary 6.4%
Utilities 5.3%
Real Estate 5.3%
Communication Services 4.3%
Materials 2.4%
Energy 1.2%
Top ten holdings
McKesson Corp. 3.1%
Johnson & Johnson 3.0%
Motorola Solutions, Inc. 2.7%
TE Connectivity PLC 2.6%
Teledyne Technologies, Inc. 2.5%
Amphenol Corp., "A" 2.4%
General Mills, Inc. 2.4%
Visa, Inc., "A" 2.3%
Cognizant Technology Solutions Corp., "A" 2.3%
Accenture PLC, "A" 2.2%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
McKesson Corp. 3.1%
Johnson & Johnson 3.0%
Motorola Solutions, Inc. 2.7%
TE Connectivity PLC 2.6%
Teledyne Technologies, Inc. 2.5%
Amphenol Corp., "A" 2.4%
General Mills, Inc. 2.4%
Visa, Inc., "A" 2.3%
Cognizant Technology Solutions Corp., "A" 2.3%
Accenture PLC, "A" 2.2%
C000132021 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Low Volatility Equity Fund
Class Name Class R6
Trading Symbol MLVTX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Low Volatility Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R6 $28 0.57%
Expenses Paid, Amount $ 28
Expense Ratio, Percent 0.57%
Net Assets $ 392,353,011
Holdings Count | Holding 106
Investment Company Portfolio Turnover 11.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 392,353,011 Portfolio Turnover Rate (%): 11
Total Number of Holdings: 106
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 99.8%
Money Market Funds 0.2%
Equity sectors
Information Technology 23.3%
Health Care 15.4%
Financials 14.2%
Industrials 11.4%
Consumer Staples 10.6%
Consumer Discretionary 6.4%
Utilities 5.3%
Real Estate 5.3%
Communication Services 4.3%
Materials 2.4%
Energy 1.2%
Top ten holdings
McKesson Corp. 3.1%
Johnson & Johnson 3.0%
Motorola Solutions, Inc. 2.7%
TE Connectivity PLC 2.6%
Teledyne Technologies, Inc. 2.5%
Amphenol Corp., "A" 2.4%
General Mills, Inc. 2.4%
Visa, Inc., "A" 2.3%
Cognizant Technology Solutions Corp., "A" 2.3%
Accenture PLC, "A" 2.2%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
McKesson Corp. 3.1%
Johnson & Johnson 3.0%
Motorola Solutions, Inc. 2.7%
TE Connectivity PLC 2.6%
Teledyne Technologies, Inc. 2.5%
Amphenol Corp., "A" 2.4%
General Mills, Inc. 2.4%
Visa, Inc., "A" 2.3%
Cognizant Technology Solutions Corp., "A" 2.3%
Accenture PLC, "A" 2.2%
C000132022 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Low Volatility Global Equity Fund
Class Name Class A
Trading Symbol MVGAX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Low Volatility Global Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
A $49 0.99%
Expenses Paid, Amount $ 49
Expense Ratio, Percent 0.99%
Net Assets $ 265,320,966
Holdings Count | Holding 105
Investment Company Portfolio Turnover 12.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 265,320,966 Portfolio Turnover Rate (%): 12
Total Number of Holdings: 105
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 100.0%
Money Market Funds 0.0%
Top ten holdings
McKesson Corp. 3.3%
DBS Group Holdings Ltd. 3.2%
Colgate-Palmolive Co. 2.8%
Roche Holding AG 2.5%
Constellation Software, Inc. 2.4%
Microsoft Corp. 2.2%
Johnson & Johnson 2.2%
Koninklijke KPN N.V. 2.1%
Franco-Nevada Corp. 2.1%
JPMorgan Chase & Co. 2.0%
Issuer country weightings
United States 56.5%
Canada 7.2%
Japan 6.3%
Singapore 6.0%
Switzerland 3.9%
United Kingdom 3.3%
Thailand 2.9%
Philippines 2.7%
France 2.1%
Other Countries 9.1%
Largest Holdings [Text Block]
Top ten holdings
McKesson Corp. 3.3%
DBS Group Holdings Ltd. 3.2%
Colgate-Palmolive Co. 2.8%
Roche Holding AG 2.5%
Constellation Software, Inc. 2.4%
Microsoft Corp. 2.2%
Johnson & Johnson 2.2%
Koninklijke KPN N.V. 2.1%
Franco-Nevada Corp. 2.1%
JPMorgan Chase & Co. 2.0%
C000132023 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Low Volatility Global Equity Fund
Class Name Class B
Trading Symbol MVGBX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Low Volatility Global Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
B $86 1.74%
Expenses Paid, Amount $ 86
Expense Ratio, Percent 1.74%
Net Assets $ 265,320,966
Holdings Count | Holding 105
Investment Company Portfolio Turnover 12.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 265,320,966 Portfolio Turnover Rate (%): 12
Total Number of Holdings: 105
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 100.0%
Money Market Funds 0.0%
Top ten holdings
McKesson Corp. 3.3%
DBS Group Holdings Ltd. 3.2%
Colgate-Palmolive Co. 2.8%
Roche Holding AG 2.5%
Constellation Software, Inc. 2.4%
Microsoft Corp. 2.2%
Johnson & Johnson 2.2%
Koninklijke KPN N.V. 2.1%
Franco-Nevada Corp. 2.1%
JPMorgan Chase & Co. 2.0%
Issuer country weightings
United States 56.5%
Canada 7.2%
Japan 6.3%
Singapore 6.0%
Switzerland 3.9%
United Kingdom 3.3%
Thailand 2.9%
Philippines 2.7%
France 2.1%
Other Countries 9.1%
Largest Holdings [Text Block]
Top ten holdings
McKesson Corp. 3.3%
DBS Group Holdings Ltd. 3.2%
Colgate-Palmolive Co. 2.8%
Roche Holding AG 2.5%
Constellation Software, Inc. 2.4%
Microsoft Corp. 2.2%
Johnson & Johnson 2.2%
Koninklijke KPN N.V. 2.1%
Franco-Nevada Corp. 2.1%
JPMorgan Chase & Co. 2.0%
C000132024 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Low Volatility Global Equity Fund
Class Name Class C
Trading Symbol MVGCX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Low Volatility Global Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
C $86 1.74%
Expenses Paid, Amount $ 86
Expense Ratio, Percent 1.74%
Net Assets $ 265,320,966
Holdings Count | Holding 105
Investment Company Portfolio Turnover 12.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 265,320,966 Portfolio Turnover Rate (%): 12
Total Number of Holdings: 105
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 100.0%
Money Market Funds 0.0%
Top ten holdings
McKesson Corp. 3.3%
DBS Group Holdings Ltd. 3.2%
Colgate-Palmolive Co. 2.8%
Roche Holding AG 2.5%
Constellation Software, Inc. 2.4%
Microsoft Corp. 2.2%
Johnson & Johnson 2.2%
Koninklijke KPN N.V. 2.1%
Franco-Nevada Corp. 2.1%
JPMorgan Chase & Co. 2.0%
Issuer country weightings
United States 56.5%
Canada 7.2%
Japan 6.3%
Singapore 6.0%
Switzerland 3.9%
United Kingdom 3.3%
Thailand 2.9%
Philippines 2.7%
France 2.1%
Other Countries 9.1%
Largest Holdings [Text Block]
Top ten holdings
McKesson Corp. 3.3%
DBS Group Holdings Ltd. 3.2%
Colgate-Palmolive Co. 2.8%
Roche Holding AG 2.5%
Constellation Software, Inc. 2.4%
Microsoft Corp. 2.2%
Johnson & Johnson 2.2%
Koninklijke KPN N.V. 2.1%
Franco-Nevada Corp. 2.1%
JPMorgan Chase & Co. 2.0%
C000132025 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Low Volatility Global Equity Fund
Class Name Class I
Trading Symbol MVGIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Low Volatility Global Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
I $37 0.74%
Expenses Paid, Amount $ 37
Expense Ratio, Percent 0.74%
Net Assets $ 265,320,966
Holdings Count | Holding 105
Investment Company Portfolio Turnover 12.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 265,320,966 Portfolio Turnover Rate (%): 12
Total Number of Holdings: 105
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 100.0%
Money Market Funds 0.0%
Top ten holdings
McKesson Corp. 3.3%
DBS Group Holdings Ltd. 3.2%
Colgate-Palmolive Co. 2.8%
Roche Holding AG 2.5%
Constellation Software, Inc. 2.4%
Microsoft Corp. 2.2%
Johnson & Johnson 2.2%
Koninklijke KPN N.V. 2.1%
Franco-Nevada Corp. 2.1%
JPMorgan Chase & Co. 2.0%
Issuer country weightings
United States 56.5%
Canada 7.2%
Japan 6.3%
Singapore 6.0%
Switzerland 3.9%
United Kingdom 3.3%
Thailand 2.9%
Philippines 2.7%
France 2.1%
Other Countries 9.1%
Largest Holdings [Text Block]
Top ten holdings
McKesson Corp. 3.3%
DBS Group Holdings Ltd. 3.2%
Colgate-Palmolive Co. 2.8%
Roche Holding AG 2.5%
Constellation Software, Inc. 2.4%
Microsoft Corp. 2.2%
Johnson & Johnson 2.2%
Koninklijke KPN N.V. 2.1%
Franco-Nevada Corp. 2.1%
JPMorgan Chase & Co. 2.0%
C000132026 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Low Volatility Global Equity Fund
Class Name Class R1
Trading Symbol MVGJX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Low Volatility Global Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R1 $86 1.74%
Expenses Paid, Amount $ 86
Expense Ratio, Percent 1.74%
Net Assets $ 265,320,966
Holdings Count | Holding 105
Investment Company Portfolio Turnover 12.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 265,320,966 Portfolio Turnover Rate (%): 12
Total Number of Holdings: 105
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 100.0%
Money Market Funds 0.0%
Top ten holdings
McKesson Corp. 3.3%
DBS Group Holdings Ltd. 3.2%
Colgate-Palmolive Co. 2.8%
Roche Holding AG 2.5%
Constellation Software, Inc. 2.4%
Microsoft Corp. 2.2%
Johnson & Johnson 2.2%
Koninklijke KPN N.V. 2.1%
Franco-Nevada Corp. 2.1%
JPMorgan Chase & Co. 2.0%
Issuer country weightings
United States 56.5%
Canada 7.2%
Japan 6.3%
Singapore 6.0%
Switzerland 3.9%
United Kingdom 3.3%
Thailand 2.9%
Philippines 2.7%
France 2.1%
Other Countries 9.1%
Largest Holdings [Text Block]
Top ten holdings
McKesson Corp. 3.3%
DBS Group Holdings Ltd. 3.2%
Colgate-Palmolive Co. 2.8%
Roche Holding AG 2.5%
Constellation Software, Inc. 2.4%
Microsoft Corp. 2.2%
Johnson & Johnson 2.2%
Koninklijke KPN N.V. 2.1%
Franco-Nevada Corp. 2.1%
JPMorgan Chase & Co. 2.0%
C000132027 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Low Volatility Global Equity Fund
Class Name Class R2
Trading Symbol MVGKX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Low Volatility Global Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R2 $61 1.24%
Expenses Paid, Amount $ 61
Expense Ratio, Percent 1.24%
Net Assets $ 265,320,966
Holdings Count | Holding 105
Investment Company Portfolio Turnover 12.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 265,320,966 Portfolio Turnover Rate (%): 12
Total Number of Holdings: 105
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 100.0%
Money Market Funds 0.0%
Top ten holdings
McKesson Corp. 3.3%
DBS Group Holdings Ltd. 3.2%
Colgate-Palmolive Co. 2.8%
Roche Holding AG 2.5%
Constellation Software, Inc. 2.4%
Microsoft Corp. 2.2%
Johnson & Johnson 2.2%
Koninklijke KPN N.V. 2.1%
Franco-Nevada Corp. 2.1%
JPMorgan Chase & Co. 2.0%
Issuer country weightings
United States 56.5%
Canada 7.2%
Japan 6.3%
Singapore 6.0%
Switzerland 3.9%
United Kingdom 3.3%
Thailand 2.9%
Philippines 2.7%
France 2.1%
Other Countries 9.1%
Largest Holdings [Text Block]
Top ten holdings
McKesson Corp. 3.3%
DBS Group Holdings Ltd. 3.2%
Colgate-Palmolive Co. 2.8%
Roche Holding AG 2.5%
Constellation Software, Inc. 2.4%
Microsoft Corp. 2.2%
Johnson & Johnson 2.2%
Koninklijke KPN N.V. 2.1%
Franco-Nevada Corp. 2.1%
JPMorgan Chase & Co. 2.0%
C000132028 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Low Volatility Global Equity Fund
Class Name Class R3
Trading Symbol MVGLX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Low Volatility Global Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R3 $49 0.99%
Expenses Paid, Amount $ 49
Expense Ratio, Percent 0.99%
Net Assets $ 265,320,966
Holdings Count | Holding 105
Investment Company Portfolio Turnover 12.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 265,320,966 Portfolio Turnover Rate (%): 12
Total Number of Holdings: 105
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 100.0%
Money Market Funds 0.0%
Top ten holdings
McKesson Corp. 3.3%
DBS Group Holdings Ltd. 3.2%
Colgate-Palmolive Co. 2.8%
Roche Holding AG 2.5%
Constellation Software, Inc. 2.4%
Microsoft Corp. 2.2%
Johnson & Johnson 2.2%
Koninklijke KPN N.V. 2.1%
Franco-Nevada Corp. 2.1%
JPMorgan Chase & Co. 2.0%
Issuer country weightings
United States 56.5%
Canada 7.2%
Japan 6.3%
Singapore 6.0%
Switzerland 3.9%
United Kingdom 3.3%
Thailand 2.9%
Philippines 2.7%
France 2.1%
Other Countries 9.1%
Largest Holdings [Text Block]
Top ten holdings
McKesson Corp. 3.3%
DBS Group Holdings Ltd. 3.2%
Colgate-Palmolive Co. 2.8%
Roche Holding AG 2.5%
Constellation Software, Inc. 2.4%
Microsoft Corp. 2.2%
Johnson & Johnson 2.2%
Koninklijke KPN N.V. 2.1%
Franco-Nevada Corp. 2.1%
JPMorgan Chase & Co. 2.0%
C000132029 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Low Volatility Global Equity Fund
Class Name Class R4
Trading Symbol MVGMX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Low Volatility Global Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R4 $37 0.74%
Expenses Paid, Amount $ 37
Expense Ratio, Percent 0.74%
Net Assets $ 265,320,966
Holdings Count | Holding 105
Investment Company Portfolio Turnover 12.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 265,320,966 Portfolio Turnover Rate (%): 12
Total Number of Holdings: 105
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 100.0%
Money Market Funds 0.0%
Top ten holdings
McKesson Corp. 3.3%
DBS Group Holdings Ltd. 3.2%
Colgate-Palmolive Co. 2.8%
Roche Holding AG 2.5%
Constellation Software, Inc. 2.4%
Microsoft Corp. 2.2%
Johnson & Johnson 2.2%
Koninklijke KPN N.V. 2.1%
Franco-Nevada Corp. 2.1%
JPMorgan Chase & Co. 2.0%
Issuer country weightings
United States 56.5%
Canada 7.2%
Japan 6.3%
Singapore 6.0%
Switzerland 3.9%
United Kingdom 3.3%
Thailand 2.9%
Philippines 2.7%
France 2.1%
Other Countries 9.1%
Largest Holdings [Text Block]
Top ten holdings
McKesson Corp. 3.3%
DBS Group Holdings Ltd. 3.2%
Colgate-Palmolive Co. 2.8%
Roche Holding AG 2.5%
Constellation Software, Inc. 2.4%
Microsoft Corp. 2.2%
Johnson & Johnson 2.2%
Koninklijke KPN N.V. 2.1%
Franco-Nevada Corp. 2.1%
JPMorgan Chase & Co. 2.0%
C000132030 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Low Volatility Global Equity Fund
Class Name Class R6
Trading Symbol MVGNX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Low Volatility Global Equity Fund for the period of September 1, 2024 to February 28, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R6 $32 0.65%
Expenses Paid, Amount $ 32
Expense Ratio, Percent 0.65%
Net Assets $ 265,320,966
Holdings Count | Holding 105
Investment Company Portfolio Turnover 12.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 2/28/25
Net Assets ($): 265,320,966 Portfolio Turnover Rate (%): 12
Total Number of Holdings: 105
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 2/28/25)
Portfolio structure
Equities 100.0%
Money Market Funds 0.0%
Top ten holdings
McKesson Corp. 3.3%
DBS Group Holdings Ltd. 3.2%
Colgate-Palmolive Co. 2.8%
Roche Holding AG 2.5%
Constellation Software, Inc. 2.4%
Microsoft Corp. 2.2%
Johnson & Johnson 2.2%
Koninklijke KPN N.V. 2.1%
Franco-Nevada Corp. 2.1%
JPMorgan Chase & Co. 2.0%
Issuer country weightings
United States 56.5%
Canada 7.2%
Japan 6.3%
Singapore 6.0%
Switzerland 3.9%
United Kingdom 3.3%
Thailand 2.9%
Philippines 2.7%
France 2.1%
Other Countries 9.1%
Largest Holdings [Text Block]
Top ten holdings
McKesson Corp. 3.3%
DBS Group Holdings Ltd. 3.2%
Colgate-Palmolive Co. 2.8%
Roche Holding AG 2.5%
Constellation Software, Inc. 2.4%
Microsoft Corp. 2.2%
Johnson & Johnson 2.2%
Koninklijke KPN N.V. 2.1%
Franco-Nevada Corp. 2.1%
JPMorgan Chase & Co. 2.0%