v3.26.1
Shareholder Report
 6 Months Ended
Apr. 30, 2026
USD ($)
Holding
Shareholder Report [Line Items]  
Document Type N-CSRS
Amendment Flag false
Registrant Name MFS SERIES TRUST VI
Entity Central Index Key 0000863032
Entity Investment Company Type N-1A
Document Period End Date Apr. 30, 2026
C000111485 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Global Equity Fund
Class Name Class R6
Trading Symbol MWEMX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Global Equity Fund for the period of November 1, 2025 to April 30, 2026.
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 $41 0.82%
Expenses Paid, Amount $ 41
Expense Ratio, Percent 0.82%
Net Assets $ 1,505,412,419
Holdings Count | Holding 81
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 1,505,412,419 Portfolio Turnover Rate (%): 19
Total Number of Holdings: 81
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 4/30/26)
Portfolio structure
Equities 99.0%
Money Market Funds 1.0%
Top ten holdings
Microsoft Corp. 4.5%
Amazon.com, Inc. 4.5%
Alphabet, Inc., "A" 4.5%
Visa, Inc., "A" 3.3%
Broadcom, Inc. 3.0%
NVIDIA Corp. 3.0%
Charles Schwab Corp. 2.5%
Schneider Electric SE 2.5%
Willis Towers Watson PLC 2.2%
Medtronic PLC 2.1%
Issuer country weightings
United States 57.9%
France 10.2%
United Kingdom 9.3%
Switzerland 4.4%
Germany 4.3%
Spain 3.0%
Japan 2.1%
Canada 1.6%
Taiwan 1.4%
Other Countries 5.8%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 4.5%
Amazon.com, Inc. 4.5%
Alphabet, Inc., "A" 4.5%
Visa, Inc., "A" 3.3%
Broadcom, Inc. 3.0%
NVIDIA Corp. 3.0%
Charles Schwab Corp. 2.5%
Schneider Electric SE 2.5%
Willis Towers Watson PLC 2.2%
Medtronic PLC 2.1%
C000006616 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Global Equity Fund
Class Name Class R4
Trading Symbol MWELX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Global Equity Fund for the period of November 1, 2025 to April 30, 2026.
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 $45 0.91%
Expenses Paid, Amount $ 45
Expense Ratio, Percent 0.91%
Net Assets $ 1,505,412,419
Holdings Count | Holding 81
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 1,505,412,419 Portfolio Turnover Rate (%): 19
Total Number of Holdings: 81
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 4/30/26)
Portfolio structure
Equities 99.0%
Money Market Funds 1.0%
Top ten holdings
Microsoft Corp. 4.5%
Amazon.com, Inc. 4.5%
Alphabet, Inc., "A" 4.5%
Visa, Inc., "A" 3.3%
Broadcom, Inc. 3.0%
NVIDIA Corp. 3.0%
Charles Schwab Corp. 2.5%
Schneider Electric SE 2.5%
Willis Towers Watson PLC 2.2%
Medtronic PLC 2.1%
Issuer country weightings
United States 57.9%
France 10.2%
United Kingdom 9.3%
Switzerland 4.4%
Germany 4.3%
Spain 3.0%
Japan 2.1%
Canada 1.6%
Taiwan 1.4%
Other Countries 5.8%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 4.5%
Amazon.com, Inc. 4.5%
Alphabet, Inc., "A" 4.5%
Visa, Inc., "A" 3.3%
Broadcom, Inc. 3.0%
NVIDIA Corp. 3.0%
Charles Schwab Corp. 2.5%
Schneider Electric SE 2.5%
Willis Towers Watson PLC 2.2%
Medtronic PLC 2.1%
C000006624 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Global Equity Fund
Class Name Class R3
Trading Symbol MWEHX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Global Equity Fund for the period of November 1, 2025 to April 30, 2026.
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 $58 1.16%
Expenses Paid, Amount $ 58
Expense Ratio, Percent 1.16%
Net Assets $ 1,505,412,419
Holdings Count | Holding 81
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 1,505,412,419 Portfolio Turnover Rate (%): 19
Total Number of Holdings: 81
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 4/30/26)
Portfolio structure
Equities 99.0%
Money Market Funds 1.0%
Top ten holdings
Microsoft Corp. 4.5%
Amazon.com, Inc. 4.5%
Alphabet, Inc., "A" 4.5%
Visa, Inc., "A" 3.3%
Broadcom, Inc. 3.0%
NVIDIA Corp. 3.0%
Charles Schwab Corp. 2.5%
Schneider Electric SE 2.5%
Willis Towers Watson PLC 2.2%
Medtronic PLC 2.1%
Issuer country weightings
United States 57.9%
France 10.2%
United Kingdom 9.3%
Switzerland 4.4%
Germany 4.3%
Spain 3.0%
Japan 2.1%
Canada 1.6%
Taiwan 1.4%
Other Countries 5.8%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 4.5%
Amazon.com, Inc. 4.5%
Alphabet, Inc., "A" 4.5%
Visa, Inc., "A" 3.3%
Broadcom, Inc. 3.0%
NVIDIA Corp. 3.0%
Charles Schwab Corp. 2.5%
Schneider Electric SE 2.5%
Willis Towers Watson PLC 2.2%
Medtronic PLC 2.1%
C000006623 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Global Equity Fund
Class Name Class R2
Trading Symbol MEQRX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Global Equity Fund for the period of November 1, 2025 to April 30, 2026.
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 1.41%
Expenses Paid, Amount $ 70
Expense Ratio, Percent 1.41%
Net Assets $ 1,505,412,419
Holdings Count | Holding 81
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 1,505,412,419 Portfolio Turnover Rate (%): 19
Total Number of Holdings: 81
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 4/30/26)

Portfolio structure

Equities 99.0%
Money Market Funds 1.0%

Top ten holdings

Microsoft Corp. 4.5%
Amazon.com, Inc. 4.5%
Alphabet, Inc., "A" 4.5%
Visa, Inc., "A" 3.3%
Broadcom, Inc. 3.0%
NVIDIA Corp. 3.0%
Charles Schwab Corp. 2.5%
Schneider Electric SE 2.5%
Willis Towers Watson PLC 2.2%
Medtronic PLC 2.1%

Issuer country weightings

United States 57.9%
France 10.2%
United Kingdom 9.3%
Switzerland 4.4%
Germany 4.3%
Spain 3.0%
Japan 2.1%
Canada 1.6%
Taiwan 1.4%
Other Countries 5.8%
Largest Holdings [Text Block]

Top ten holdings

Microsoft Corp. 4.5%
Amazon.com, Inc. 4.5%
Alphabet, Inc., "A" 4.5%
Visa, Inc., "A" 3.3%
Broadcom, Inc. 3.0%
NVIDIA Corp. 3.0%
Charles Schwab Corp. 2.5%
Schneider Electric SE 2.5%
Willis Towers Watson PLC 2.2%
Medtronic PLC 2.1%
C000006618 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Global Equity Fund
Class Name Class C
Trading Symbol MWECX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Global Equity Fund for the period of November 1, 2025 to April 30, 2026.
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 $95 1.91%
Expenses Paid, Amount $ 95
Expense Ratio, Percent 1.91%
Net Assets $ 1,505,412,419
Holdings Count | Holding 81
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 1,505,412,419 Portfolio Turnover Rate (%): 19
Total Number of Holdings: 81
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 4/30/26)
Portfolio structure
Equities 99.0%
Money Market Funds 1.0%
Top ten holdings
Microsoft Corp. 4.5%
Amazon.com, Inc. 4.5%
Alphabet, Inc., "A" 4.5%
Visa, Inc., "A" 3.3%
Broadcom, Inc. 3.0%
NVIDIA Corp. 3.0%
Charles Schwab Corp. 2.5%
Schneider Electric SE 2.5%
Willis Towers Watson PLC 2.2%
Medtronic PLC 2.1%
Issuer country weightings
United States 57.9%
France 10.2%
United Kingdom 9.3%
Switzerland 4.4%
Germany 4.3%
Spain 3.0%
Japan 2.1%
Canada 1.6%
Taiwan 1.4%
Other Countries 5.8%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 4.5%
Amazon.com, Inc. 4.5%
Alphabet, Inc., "A" 4.5%
Visa, Inc., "A" 3.3%
Broadcom, Inc. 3.0%
NVIDIA Corp. 3.0%
Charles Schwab Corp. 2.5%
Schneider Electric SE 2.5%
Willis Towers Watson PLC 2.2%
Medtronic PLC 2.1%
C000006617 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Global Equity Fund
Class Name Class B
Trading Symbol MWEBX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Global Equity Fund for the period of November 1, 2025 to April 30, 2026.
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 $95 1.91%
Expenses Paid, Amount $ 95
Expense Ratio, Percent 1.91%
Net Assets $ 1,505,412,419
Holdings Count | Holding 81
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 1,505,412,419 Portfolio Turnover Rate (%): 19
Total Number of Holdings: 81
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 4/30/26)
Portfolio structure
Equities 99.0%
Money Market Funds 1.0%
Top ten holdings
Microsoft Corp. 4.5%
Amazon.com, Inc. 4.5%
Alphabet, Inc., "A" 4.5%
Visa, Inc., "A" 3.3%
Broadcom, Inc. 3.0%
NVIDIA Corp. 3.0%
Charles Schwab Corp. 2.5%
Schneider Electric SE 2.5%
Willis Towers Watson PLC 2.2%
Medtronic PLC 2.1%
Issuer country weightings
United States 57.9%
France 10.2%
United Kingdom 9.3%
Switzerland 4.4%
Germany 4.3%
Spain 3.0%
Japan 2.1%
Canada 1.6%
Taiwan 1.4%
Other Countries 5.8%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 4.5%
Amazon.com, Inc. 4.5%
Alphabet, Inc., "A" 4.5%
Visa, Inc., "A" 3.3%
Broadcom, Inc. 3.0%
NVIDIA Corp. 3.0%
Charles Schwab Corp. 2.5%
Schneider Electric SE 2.5%
Willis Towers Watson PLC 2.2%
Medtronic PLC 2.1%
C000006619 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Global Equity Fund
Class Name Class I
Trading Symbol MWEIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Global Equity Fund for the period of November 1, 2025 to April 30, 2026.
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 $45 0.91%
Expenses Paid, Amount $ 45
Expense Ratio, Percent 0.91%
Net Assets $ 1,505,412,419
Holdings Count | Holding 81
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 1,505,412,419 Portfolio Turnover Rate (%): 19
Total Number of Holdings: 81
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 4/30/26)
Portfolio structure
Equities 99.0%
Money Market Funds 1.0%
Top ten holdings
Microsoft Corp. 4.5%
Amazon.com, Inc. 4.5%
Alphabet, Inc., "A" 4.5%
Visa, Inc., "A" 3.3%
Broadcom, Inc. 3.0%
NVIDIA Corp. 3.0%
Charles Schwab Corp. 2.5%
Schneider Electric SE 2.5%
Willis Towers Watson PLC 2.2%
Medtronic PLC 2.1%
Issuer country weightings
United States 57.9%
France 10.2%
United Kingdom 9.3%
Switzerland 4.4%
Germany 4.3%
Spain 3.0%
Japan 2.1%
Canada 1.6%
Taiwan 1.4%
Other Countries 5.8%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 4.5%
Amazon.com, Inc. 4.5%
Alphabet, Inc., "A" 4.5%
Visa, Inc., "A" 3.3%
Broadcom, Inc. 3.0%
NVIDIA Corp. 3.0%
Charles Schwab Corp. 2.5%
Schneider Electric SE 2.5%
Willis Towers Watson PLC 2.2%
Medtronic PLC 2.1%
C000006621 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Global Equity Fund
Class Name Class R1
Trading Symbol MWEGX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Global Equity Fund for the period of November 1, 2025 to April 30, 2026.
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 $95 1.91%
Expenses Paid, Amount $ 95
Expense Ratio, Percent 1.91%
Net Assets $ 1,505,412,419
Holdings Count | Holding 81
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 1,505,412,419 Portfolio Turnover Rate (%): 19
Total Number of Holdings: 81
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 4/30/26)
Portfolio structure
Equities 99.0%
Money Market Funds 1.0%
Top ten holdings
Microsoft Corp. 4.5%
Amazon.com, Inc. 4.5%
Alphabet, Inc., "A" 4.5%
Visa, Inc., "A" 3.3%
Broadcom, Inc. 3.0%
NVIDIA Corp. 3.0%
Charles Schwab Corp. 2.5%
Schneider Electric SE 2.5%
Willis Towers Watson PLC 2.2%
Medtronic PLC 2.1%
Issuer country weightings
United States 57.9%
France 10.2%
United Kingdom 9.3%
Switzerland 4.4%
Germany 4.3%
Spain 3.0%
Japan 2.1%
Canada 1.6%
Taiwan 1.4%
Other Countries 5.8%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 4.5%
Amazon.com, Inc. 4.5%
Alphabet, Inc., "A" 4.5%
Visa, Inc., "A" 3.3%
Broadcom, Inc. 3.0%
NVIDIA Corp. 3.0%
Charles Schwab Corp. 2.5%
Schneider Electric SE 2.5%
Willis Towers Watson PLC 2.2%
Medtronic PLC 2.1%
C000006615 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Global Equity Fund
Class Name Class A
Trading Symbol MWEFX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Global Equity Fund for the period of November 1, 2025 to April 30, 2026.
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 $58 1.16%
Expenses Paid, Amount $ 58
Expense Ratio, Percent 1.16%
Net Assets $ 1,505,412,419
Holdings Count | Holding 81
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 1,505,412,419 Portfolio Turnover Rate (%): 19
Total Number of Holdings: 81
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 4/30/26)
Portfolio structure
Equities 99.0%
Money Market Funds 1.0%
Top ten holdings
Microsoft Corp. 4.5%
Amazon.com, Inc. 4.5%
Alphabet, Inc., "A" 4.5%
Visa, Inc., "A" 3.3%
Broadcom, Inc. 3.0%
NVIDIA Corp. 3.0%
Charles Schwab Corp. 2.5%
Schneider Electric SE 2.5%
Willis Towers Watson PLC 2.2%
Medtronic PLC 2.1%
Issuer country weightings
United States 57.9%
France 10.2%
United Kingdom 9.3%
Switzerland 4.4%
Germany 4.3%
Spain 3.0%
Japan 2.1%
Canada 1.6%
Taiwan 1.4%
Other Countries 5.8%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 4.5%
Amazon.com, Inc. 4.5%
Alphabet, Inc., "A" 4.5%
Visa, Inc., "A" 3.3%
Broadcom, Inc. 3.0%
NVIDIA Corp. 3.0%
Charles Schwab Corp. 2.5%
Schneider Electric SE 2.5%
Willis Towers Watson PLC 2.2%
Medtronic PLC 2.1%
C000006625 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Global TotalReturn Fund
Class Name Class A
Trading Symbol MFWTX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Global Total Return Fund for the period of November 1, 2025 to April 30, 2026.
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 $56 1.09%
Expenses Paid, Amount $ 56
Expense Ratio, Percent 1.09%
Net Assets $ 1,242,566,076
Holdings Count | Holding 814
Investment Company Portfolio Turnover 33.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 1,242,566,076 Portfolio Turnover Rate (%): 33
Total Number of Holdings: 814
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 4/30/26)
Portfolio structure
Equities 60.2%
Fixed Income 36.6%
Money Market Funds 3.2%
Equity sectors
Financials 13.5%
Health Care 8.6%
Consumer Staples 7.4%
Industrials 7.4%
Information Technology 5.9%
Energy 5.4%
Utilities 3.3%
Consumer Discretionary 3.1%
Communication Services 2.7%
Materials 2.6%
Real Estate 0.3%
Issuer country weightings
United States 47.7%
United Kingdom 9.5%
France 6.7%
Japan 5.9%
China 4.3%
Canada 3.5%
Switzerland 3.0%
Italy 3.0%
South Korea 2.5%
Other Countries 13.9%
Composition including fixed income credit quality
AAA 4.3%
AA 3.7%
A 11.1%
BBB 8.9%
D 0.0%
U.S. Government 3.6%
Federal Agencies 3.6%
Not Rated 1.4%
Non-Fixed Income 60.2%
Money Market Funds 3.2%
Ratings are assigned using Moody’s, Fitch, and Standard & Poor’s and applying a hierarchy: If all 3 agencies rate a security, the middle rating is assigned; if 2 agencies rate a security, the lower rating is assigned. If none of the 3 agencies rate a security, we use DBRS Morningstar. If none of the 4 agencies rate a security, we use Kroll Bond Rating Agency. Ratings are shown in the S&P and Fitch scale (e.g., AAA). All ratings are subject to change.
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.
Credit Ratings Selection [Text Block]
Ratings are assigned using Moody’s, Fitch, and Standard & Poor’s and applying a hierarchy: If all 3 agencies rate a security, the middle rating is assigned; if 2 agencies rate a security, the lower rating is assigned. If none of the 3 agencies rate a security, we use DBRS Morningstar. If none of the 4 agencies rate a security, we use Kroll Bond Rating Agency. Ratings are shown in the S&P and Fitch scale (e.g., AAA). All ratings are subject to change.
C000006627 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Global TotalReturn Fund
Class Name Class B
Trading Symbol MFWBX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Global Total Return Fund for the period of November 1, 2025 to April 30, 2026.
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 $95 1.84%
Expenses Paid, Amount $ 95
Expense Ratio, Percent 1.84%
Net Assets $ 1,242,566,076
Holdings Count | Holding 814
Investment Company Portfolio Turnover 33.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 1,242,566,076 Portfolio Turnover Rate (%): 33
Total Number of Holdings: 814
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 4/30/26)
Portfolio structure
Equities 60.2%
Fixed Income 36.6%
Money Market Funds 3.2%
Equity sectors
Financials 13.5%
Health Care 8.6%
Consumer Staples 7.4%
Industrials 7.4%
Information Technology 5.9%
Energy 5.4%
Utilities 3.3%
Consumer Discretionary 3.1%
Communication Services 2.7%
Materials 2.6%
Real Estate 0.3%
Issuer country weightings
United States 47.7%
United Kingdom 9.5%
France 6.7%
Japan 5.9%
China 4.3%
Canada 3.5%
Switzerland 3.0%
Italy 3.0%
South Korea 2.5%
Other Countries 13.9%
Composition including fixed income credit quality
AAA 4.3%
AA 3.7%
A 11.1%
BBB 8.9%
D 0.0%
U.S. Government 3.6%
Federal Agencies 3.6%
Not Rated 1.4%
Non-Fixed Income 60.2%
Money Market Funds 3.2%
Ratings are assigned using Moody’s, Fitch, and Standard & Poor’s and applying a hierarchy: If all 3 agencies rate a security, the middle rating is assigned; if 2 agencies rate a security, the lower rating is assigned. If none of the 3 agencies rate a security, we use DBRS Morningstar. If none of the 4 agencies rate a security, we use Kroll Bond Rating Agency. Ratings are shown in the S&P and Fitch scale (e.g., AAA). All ratings are subject to change.
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.
Credit Ratings Selection [Text Block]
Ratings are assigned using Moody’s, Fitch, and Standard & Poor’s and applying a hierarchy: If all 3 agencies rate a security, the middle rating is assigned; if 2 agencies rate a security, the lower rating is assigned. If none of the 3 agencies rate a security, we use DBRS Morningstar. If none of the 4 agencies rate a security, we use Kroll Bond Rating Agency. Ratings are shown in the S&P and Fitch scale (e.g., AAA). All ratings are subject to change.
C000006628 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Global TotalReturn Fund
Class Name Class C
Trading Symbol MFWCX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Global Total Return Fund for the period of November 1, 2025 to April 30, 2026.
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 $95 1.84%
Expenses Paid, Amount $ 95
Expense Ratio, Percent 1.84%
Net Assets $ 1,242,566,076
Holdings Count | Holding 814
Investment Company Portfolio Turnover 33.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 1,242,566,076 Portfolio Turnover Rate (%): 33
Total Number of Holdings: 814
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 4/30/26)
Portfolio structure
Equities 60.2%
Fixed Income 36.6%
Money Market Funds 3.2%
Equity sectors
Financials 13.5%
Health Care 8.6%
Consumer Staples 7.4%
Industrials 7.4%
Information Technology 5.9%
Energy 5.4%
Utilities 3.3%
Consumer Discretionary 3.1%
Communication Services 2.7%
Materials 2.6%
Real Estate 0.3%
Issuer country weightings
United States 47.7%
United Kingdom 9.5%
France 6.7%
Japan 5.9%
China 4.3%
Canada 3.5%
Switzerland 3.0%
Italy 3.0%
South Korea 2.5%
Other Countries 13.9%
Composition including fixed income credit quality
AAA 4.3%
AA 3.7%
A 11.1%
BBB 8.9%
D 0.0%
U.S. Government 3.6%
Federal Agencies 3.6%
Not Rated 1.4%
Non-Fixed Income 60.2%
Money Market Funds 3.2%
Ratings are assigned using Moody’s, Fitch, and Standard & Poor’s and applying a hierarchy: If all 3 agencies rate a security, the middle rating is assigned; if 2 agencies rate a security, the lower rating is assigned. If none of the 3 agencies rate a security, we use DBRS Morningstar. If none of the 4 agencies rate a security, we use Kroll Bond Rating Agency. Ratings are shown in the S&P and Fitch scale (e.g., AAA). All ratings are subject to change.
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.
Credit Ratings Selection [Text Block]
Ratings are assigned using Moody’s, Fitch, and Standard & Poor’s and applying a hierarchy: If all 3 agencies rate a security, the middle rating is assigned; if 2 agencies rate a security, the lower rating is assigned. If none of the 3 agencies rate a security, we use DBRS Morningstar. If none of the 4 agencies rate a security, we use Kroll Bond Rating Agency. Ratings are shown in the S&P and Fitch scale (e.g., AAA). All ratings are subject to change.
C000006629 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Global TotalReturn Fund
Class Name Class I
Trading Symbol MFWIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Global Total Return Fund for the period of November 1, 2025 to April 30, 2026.
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 $43 0.84%
Expenses Paid, Amount $ 43
Expense Ratio, Percent 0.84%
Net Assets $ 1,242,566,076
Holdings Count | Holding 814
Investment Company Portfolio Turnover 33.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 1,242,566,076 Portfolio Turnover Rate (%): 33
Total Number of Holdings: 814
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 4/30/26)
Portfolio structure
Equities 60.2%
Fixed Income 36.6%
Money Market Funds 3.2%
Equity sectors
Financials 13.5%
Health Care 8.6%
Consumer Staples 7.4%
Industrials 7.4%
Information Technology 5.9%
Energy 5.4%
Utilities 3.3%
Consumer Discretionary 3.1%
Communication Services 2.7%
Materials 2.6%
Real Estate 0.3%
Issuer country weightings
United States 47.7%
United Kingdom 9.5%
France 6.7%
Japan 5.9%
China 4.3%
Canada 3.5%
Switzerland 3.0%
Italy 3.0%
South Korea 2.5%
Other Countries 13.9%
Composition including fixed income credit quality
AAA 4.3%
AA 3.7%
A 11.1%
BBB 8.9%
D 0.0%
U.S. Government 3.6%
Federal Agencies 3.6%
Not Rated 1.4%
Non-Fixed Income 60.2%
Money Market Funds 3.2%
Ratings are assigned using Moody’s, Fitch, and Standard & Poor’s and applying a hierarchy: If all 3 agencies rate a security, the middle rating is assigned; if 2 agencies rate a security, the lower rating is assigned. If none of the 3 agencies rate a security, we use DBRS Morningstar. If none of the 4 agencies rate a security, we use Kroll Bond Rating Agency. Ratings are shown in the S&P and Fitch scale (e.g., AAA). All ratings are subject to change.
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.
Credit Ratings Selection [Text Block]
Ratings are assigned using Moody’s, Fitch, and Standard & Poor’s and applying a hierarchy: If all 3 agencies rate a security, the middle rating is assigned; if 2 agencies rate a security, the lower rating is assigned. If none of the 3 agencies rate a security, we use DBRS Morningstar. If none of the 4 agencies rate a security, we use Kroll Bond Rating Agency. Ratings are shown in the S&P and Fitch scale (e.g., AAA). All ratings are subject to change.
C000006631 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Global TotalReturn Fund
Class Name Class R1
Trading Symbol MFWGX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Global Total Return Fund for the period of November 1, 2025 to April 30, 2026.
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 $95 1.84%
Expenses Paid, Amount $ 95
Expense Ratio, Percent 1.84%
Net Assets $ 1,242,566,076
Holdings Count | Holding 814
Investment Company Portfolio Turnover 33.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 1,242,566,076 Portfolio Turnover Rate (%): 33
Total Number of Holdings: 814
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 4/30/26)
Portfolio structure
Equities 60.2%
Fixed Income 36.6%
Money Market Funds 3.2%
Equity sectors
Financials 13.5%
Health Care 8.6%
Consumer Staples 7.4%
Industrials 7.4%
Information Technology 5.9%
Energy 5.4%
Utilities 3.3%
Consumer Discretionary 3.1%
Communication Services 2.7%
Materials 2.6%
Real Estate 0.3%
Issuer country weightings
United States 47.7%
United Kingdom 9.5%
France 6.7%
Japan 5.9%
China 4.3%
Canada 3.5%
Switzerland 3.0%
Italy 3.0%
South Korea 2.5%
Other Countries 13.9%
Composition including fixed income credit quality
AAA 4.3%
AA 3.7%
A 11.1%
BBB 8.9%
D 0.0%
U.S. Government 3.6%
Federal Agencies 3.6%
Not Rated 1.4%
Non-Fixed Income 60.2%
Money Market Funds 3.2%
Ratings are assigned using Moody’s, Fitch, and Standard & Poor’s and applying a hierarchy: If all 3 agencies rate a security, the middle rating is assigned; if 2 agencies rate a security, the lower rating is assigned. If none of the 3 agencies rate a security, we use DBRS Morningstar. If none of the 4 agencies rate a security, we use Kroll Bond Rating Agency. Ratings are shown in the S&P and Fitch scale (e.g., AAA). All ratings are subject to change.
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.
Credit Ratings Selection [Text Block]
Ratings are assigned using Moody’s, Fitch, and Standard & Poor’s and applying a hierarchy: If all 3 agencies rate a security, the middle rating is assigned; if 2 agencies rate a security, the lower rating is assigned. If none of the 3 agencies rate a security, we use DBRS Morningstar. If none of the 4 agencies rate a security, we use Kroll Bond Rating Agency. Ratings are shown in the S&P and Fitch scale (e.g., AAA). All ratings are subject to change.
C000006633 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Global TotalReturn Fund
Class Name Class R2
Trading Symbol MGBRX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Global Total Return Fund for the period of November 1, 2025 to April 30, 2026.
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 $69 1.34%
Expenses Paid, Amount $ 69
Expense Ratio, Percent 1.34%
Net Assets $ 1,242,566,076
Holdings Count | Holding 814
Investment Company Portfolio Turnover 33.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 1,242,566,076 Portfolio Turnover Rate (%): 33
Total Number of Holdings: 814
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 4/30/26)
Portfolio structure
Equities 60.2%
Fixed Income 36.6%
Money Market Funds 3.2%
Equity sectors
Financials 13.5%
Health Care 8.6%
Consumer Staples 7.4%
Industrials 7.4%
Information Technology 5.9%
Energy 5.4%
Utilities 3.3%
Consumer Discretionary 3.1%
Communication Services 2.7%
Materials 2.6%
Real Estate 0.3%
Issuer country weightings
United States 47.7%
United Kingdom 9.5%
France 6.7%
Japan 5.9%
China 4.3%
Canada 3.5%
Switzerland 3.0%
Italy 3.0%
South Korea 2.5%
Other Countries 13.9%
Composition including fixed income credit quality
AAA 4.3%
AA 3.7%
A 11.1%
BBB 8.9%
D 0.0%
U.S. Government 3.6%
Federal Agencies 3.6%
Not Rated 1.4%
Non-Fixed Income 60.2%
Money Market Funds 3.2%
Ratings are assigned using Moody’s, Fitch, and Standard & Poor’s and applying a hierarchy: If all 3 agencies rate a security, the middle rating is assigned; if 2 agencies rate a security, the lower rating is assigned. If none of the 3 agencies rate a security, we use DBRS Morningstar. If none of the 4 agencies rate a security, we use Kroll Bond Rating Agency. Ratings are shown in the S&P and Fitch scale (e.g., AAA). All ratings are subject to change.
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.
Credit Ratings Selection [Text Block]
Ratings are assigned using Moody’s, Fitch, and Standard & Poor’s and applying a hierarchy: If all 3 agencies rate a security, the middle rating is assigned; if 2 agencies rate a security, the lower rating is assigned. If none of the 3 agencies rate a security, we use DBRS Morningstar. If none of the 4 agencies rate a security, we use Kroll Bond Rating Agency. Ratings are shown in the S&P and Fitch scale (e.g., AAA). All ratings are subject to change.
C000006634 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Global TotalReturn Fund
Class Name Class R3
Trading Symbol MFWHX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Global Total Return Fund for the period of November 1, 2025 to April 30, 2026.
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 $56 1.09%
Expenses Paid, Amount $ 56
Expense Ratio, Percent 1.09%
Net Assets $ 1,242,566,076
Holdings Count | Holding 814
Investment Company Portfolio Turnover 33.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 1,242,566,076 Portfolio Turnover Rate (%): 33
Total Number of Holdings: 814
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 4/30/26)
Portfolio structure
Equities 60.2%
Fixed Income 36.6%
Money Market Funds 3.2%
Equity sectors
Financials 13.5%
Health Care 8.6%
Consumer Staples 7.4%
Industrials 7.4%
Information Technology 5.9%
Energy 5.4%
Utilities 3.3%
Consumer Discretionary 3.1%
Communication Services 2.7%
Materials 2.6%
Real Estate 0.3%
Issuer country weightings
United States 47.7%
United Kingdom 9.5%
France 6.7%
Japan 5.9%
China 4.3%
Canada 3.5%
Switzerland 3.0%
Italy 3.0%
South Korea 2.5%
Other Countries 13.9%
Composition including fixed income credit quality
AAA 4.3%
AA 3.7%
A 11.1%
BBB 8.9%
D 0.0%
U.S. Government 3.6%
Federal Agencies 3.6%
Not Rated 1.4%
Non-Fixed Income 60.2%
Money Market Funds 3.2%
Ratings are assigned using Moody’s, Fitch, and Standard & Poor’s and applying a hierarchy: If all 3 agencies rate a security, the middle rating is assigned; if 2 agencies rate a security, the lower rating is assigned. If none of the 3 agencies rate a security, we use DBRS Morningstar. If none of the 4 agencies rate a security, we use Kroll Bond Rating Agency. Ratings are shown in the S&P and Fitch scale (e.g., AAA). All ratings are subject to change.
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.
Credit Ratings Selection [Text Block]
Ratings are assigned using Moody’s, Fitch, and Standard & Poor’s and applying a hierarchy: If all 3 agencies rate a security, the middle rating is assigned; if 2 agencies rate a security, the lower rating is assigned. If none of the 3 agencies rate a security, we use DBRS Morningstar. If none of the 4 agencies rate a security, we use Kroll Bond Rating Agency. Ratings are shown in the S&P and Fitch scale (e.g., AAA). All ratings are subject to change.
C000006626 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Global TotalReturn Fund
Class Name Class R4
Trading Symbol MFWJX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Global Total Return Fund for the period of November 1, 2025 to April 30, 2026.
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 $43 0.84%
Expenses Paid, Amount $ 43
Expense Ratio, Percent 0.84%
Net Assets $ 1,242,566,076
Holdings Count | Holding 814
Investment Company Portfolio Turnover 33.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 1,242,566,076 Portfolio Turnover Rate (%): 33
Total Number of Holdings: 814
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 4/30/26)
Portfolio structure
Equities 60.2%
Fixed Income 36.6%
Money Market Funds 3.2%
Equity sectors
Financials 13.5%
Health Care 8.6%
Consumer Staples 7.4%
Industrials 7.4%
Information Technology 5.9%
Energy 5.4%
Utilities 3.3%
Consumer Discretionary 3.1%
Communication Services 2.7%
Materials 2.6%
Real Estate 0.3%
Issuer country weightings
United States 47.7%
United Kingdom 9.5%
France 6.7%
Japan 5.9%
China 4.3%
Canada 3.5%
Switzerland 3.0%
Italy 3.0%
South Korea 2.5%
Other Countries 13.9%
Composition including fixed income credit quality
AAA 4.3%
AA 3.7%
A 11.1%
BBB 8.9%
D 0.0%
U.S. Government 3.6%
Federal Agencies 3.6%
Not Rated 1.4%
Non-Fixed Income 60.2%
Money Market Funds 3.2%
Ratings are assigned using Moody’s, Fitch, and Standard & Poor’s and applying a hierarchy: If all 3 agencies rate a security, the middle rating is assigned; if 2 agencies rate a security, the lower rating is assigned. If none of the 3 agencies rate a security, we use DBRS Morningstar. If none of the 4 agencies rate a security, we use Kroll Bond Rating Agency. Ratings are shown in the S&P and Fitch scale (e.g., AAA). All ratings are subject to change.
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.
Credit Ratings Selection [Text Block]
Ratings are assigned using Moody’s, Fitch, and Standard & Poor’s and applying a hierarchy: If all 3 agencies rate a security, the middle rating is assigned; if 2 agencies rate a security, the lower rating is assigned. If none of the 3 agencies rate a security, we use DBRS Morningstar. If none of the 4 agencies rate a security, we use Kroll Bond Rating Agency. Ratings are shown in the S&P and Fitch scale (e.g., AAA). All ratings are subject to change.
C000111486 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Global TotalReturn Fund
Class Name Class R6
Trading Symbol MFWLX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Global Total Return Fund for the period of November 1, 2025 to April 30, 2026.
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 $39 0.76%
Expenses Paid, Amount $ 39
Expense Ratio, Percent 0.76%
Net Assets $ 1,242,566,076
Holdings Count | Holding 814
Investment Company Portfolio Turnover 33.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 1,242,566,076 Portfolio Turnover Rate (%): 33
Total Number of Holdings: 814
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 4/30/26)
Portfolio structure
Equities 60.2%
Fixed Income 36.6%
Money Market Funds 3.2%
Equity sectors
Financials 13.5%
Health Care 8.6%
Consumer Staples 7.4%
Industrials 7.4%
Information Technology 5.9%
Energy 5.4%
Utilities 3.3%
Consumer Discretionary 3.1%
Communication Services 2.7%
Materials 2.6%
Real Estate 0.3%
Issuer country weightings
United States 47.7%
United Kingdom 9.5%
France 6.7%
Japan 5.9%
China 4.3%
Canada 3.5%
Switzerland 3.0%
Italy 3.0%
South Korea 2.5%
Other Countries 13.9%
Composition including fixed income credit quality
AAA 4.3%
AA 3.7%
A 11.1%
BBB 8.9%
D 0.0%
U.S. Government 3.6%
Federal Agencies 3.6%
Not Rated 1.4%
Non-Fixed Income 60.2%
Money Market Funds 3.2%
Ratings are assigned using Moody’s, Fitch, and Standard & Poor’s and applying a hierarchy: If all 3 agencies rate a security, the middle rating is assigned; if 2 agencies rate a security, the lower rating is assigned. If none of the 3 agencies rate a security, we use DBRS Morningstar. If none of the 4 agencies rate a security, we use Kroll Bond Rating Agency. Ratings are shown in the S&P and Fitch scale (e.g., AAA). All ratings are subject to change.
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.
Credit Ratings Selection [Text Block]
Ratings are assigned using Moody’s, Fitch, and Standard & Poor’s and applying a hierarchy: If all 3 agencies rate a security, the middle rating is assigned; if 2 agencies rate a security, the lower rating is assigned. If none of the 3 agencies rate a security, we use DBRS Morningstar. If none of the 4 agencies rate a security, we use Kroll Bond Rating Agency. Ratings are shown in the S&P and Fitch scale (e.g., AAA). All ratings are subject to change.
C000070410 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Utilities Fund
Class Name Class R6
Trading Symbol MMUKX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Utilities Fund for the period of November 1, 2025 to April 30, 2026.
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 $34 0.65%
Expenses Paid, Amount $ 34
Expense Ratio, Percent 0.65%
Net Assets $ 2,817,509,483
Holdings Count | Holding 36
Investment Company Portfolio Turnover 6.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 2,817,509,483 Portfolio Turnover Rate (%): 6
Total Number of Holdings: 36
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 4/30/26)
Portfolio structure
Equities 99.2%
Money Market Funds 0.8%
Top ten holdings
NextEra Energy, Inc. 13.3%
Constellation Energy 7.0%
PG&E Corp. 5.6%
Xcel Energy, Inc. 5.4%
Sempra 4.9%
American Electric Power Co., Inc. 4.9%
DTE Energy Co. 4.1%
Ameren Corp. 3.8%
Dominion Energy, Inc. 3.8%
Southern Co. 3.7%
Industry allocation
Utilities 98.1%
Energy - Renewables 1.9%
Largest Holdings [Text Block]
Top ten holdings
NextEra Energy, Inc. 13.3%
Constellation Energy 7.0%
PG&E Corp. 5.6%
Xcel Energy, Inc. 5.4%
Sempra 4.9%
American Electric Power Co., Inc. 4.9%
DTE Energy Co. 4.1%
Ameren Corp. 3.8%
Dominion Energy, Inc. 3.8%
Southern Co. 3.7%
C000006636 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Utilities Fund
Class Name Class R4
Trading Symbol MMUJX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Utilities Fund for the period of November 1, 2025 to April 30, 2026.
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 $39 0.74%
Expenses Paid, Amount $ 39
Expense Ratio, Percent 0.74%
Net Assets $ 2,817,509,483
Holdings Count | Holding 36
Investment Company Portfolio Turnover 6.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 2,817,509,483 Portfolio Turnover Rate (%): 6
Total Number of Holdings: 36
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 4/30/26)
Portfolio structure
Equities 99.2%
Money Market Funds 0.8%
Top ten holdings
NextEra Energy, Inc. 13.3%
Constellation Energy 7.0%
PG&E Corp. 5.6%
Xcel Energy, Inc. 5.4%
Sempra 4.9%
American Electric Power Co., Inc. 4.9%
DTE Energy Co. 4.1%
Ameren Corp. 3.8%
Dominion Energy, Inc. 3.8%
Southern Co. 3.7%
Industry allocation
Utilities 98.1%
Energy - Renewables 1.9%
Largest Holdings [Text Block]
Top ten holdings
NextEra Energy, Inc. 13.3%
Constellation Energy 7.0%
PG&E Corp. 5.6%
Xcel Energy, Inc. 5.4%
Sempra 4.9%
American Electric Power Co., Inc. 4.9%
DTE Energy Co. 4.1%
Ameren Corp. 3.8%
Dominion Energy, Inc. 3.8%
Southern Co. 3.7%
C000006644 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Utilities Fund
Class Name Class R3
Trading Symbol MMUHX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Utilities Fund for the period of November 1, 2025 to April 30, 2026.
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 $52 0.99%
Expenses Paid, Amount $ 52
Expense Ratio, Percent 0.99%
Net Assets $ 2,817,509,483
Holdings Count | Holding 36
Investment Company Portfolio Turnover 6.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 2,817,509,483 Portfolio Turnover Rate (%): 6
Total Number of Holdings: 36
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 4/30/26)
Portfolio structure
Equities 99.2%
Money Market Funds 0.8%
Top ten holdings
NextEra Energy, Inc. 13.3%
Constellation Energy 7.0%
PG&E Corp. 5.6%
Xcel Energy, Inc. 5.4%
Sempra 4.9%
American Electric Power Co., Inc. 4.9%
DTE Energy Co. 4.1%
Ameren Corp. 3.8%
Dominion Energy, Inc. 3.8%
Southern Co. 3.7%
Industry allocation
Utilities 98.1%
Energy - Renewables 1.9%
Largest Holdings [Text Block]
Top ten holdings
NextEra Energy, Inc. 13.3%
Constellation Energy 7.0%
PG&E Corp. 5.6%
Xcel Energy, Inc. 5.4%
Sempra 4.9%
American Electric Power Co., Inc. 4.9%
DTE Energy Co. 4.1%
Ameren Corp. 3.8%
Dominion Energy, Inc. 3.8%
Southern Co. 3.7%
C000006643 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Utilities Fund
Class Name Class R2
Trading Symbol MURRX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Utilities Fund for the period of November 1, 2025 to April 30, 2026.
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 $64 1.24%
Expenses Paid, Amount $ 64
Expense Ratio, Percent 1.24%
Net Assets $ 2,817,509,483
Holdings Count | Holding 36
Investment Company Portfolio Turnover 6.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 2,817,509,483 Portfolio Turnover Rate (%): 6
Total Number of Holdings: 36
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 4/30/26)
Portfolio structure
Equities 99.2%
Money Market Funds 0.8%
Top ten holdings
NextEra Energy, Inc. 13.3%
Constellation Energy 7.0%
PG&E Corp. 5.6%
Xcel Energy, Inc. 5.4%
Sempra 4.9%
American Electric Power Co., Inc. 4.9%
DTE Energy Co. 4.1%
Ameren Corp. 3.8%
Dominion Energy, Inc. 3.8%
Southern Co. 3.7%
Industry allocation
Utilities 98.1%
Energy - Renewables 1.9%
Largest Holdings [Text Block]
Top ten holdings
NextEra Energy, Inc. 13.3%
Constellation Energy 7.0%
PG&E Corp. 5.6%
Xcel Energy, Inc. 5.4%
Sempra 4.9%
American Electric Power Co., Inc. 4.9%
DTE Energy Co. 4.1%
Ameren Corp. 3.8%
Dominion Energy, Inc. 3.8%
Southern Co. 3.7%
C000006639 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Utilities Fund
Class Name Class I
Trading Symbol MMUIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Utilities Fund for the period of November 1, 2025 to April 30, 2026.
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 $39 0.74%
Expenses Paid, Amount $ 39
Expense Ratio, Percent 0.74%
Net Assets $ 2,817,509,483
Holdings Count | Holding 36
Investment Company Portfolio Turnover 6.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 2,817,509,483 Portfolio Turnover Rate (%): 6
Total Number of Holdings: 36
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 4/30/26)
Portfolio structure
Equities 99.2%
Money Market Funds 0.8%
Top ten holdings
NextEra Energy, Inc. 13.3%
Constellation Energy 7.0%
PG&E Corp. 5.6%
Xcel Energy, Inc. 5.4%
Sempra 4.9%
American Electric Power Co., Inc. 4.9%
DTE Energy Co. 4.1%
Ameren Corp. 3.8%
Dominion Energy, Inc. 3.8%
Southern Co. 3.7%
Industry allocation
Utilities 98.1%
Energy - Renewables 1.9%
Largest Holdings [Text Block]
Top ten holdings
NextEra Energy, Inc. 13.3%
Constellation Energy 7.0%
PG&E Corp. 5.6%
Xcel Energy, Inc. 5.4%
Sempra 4.9%
American Electric Power Co., Inc. 4.9%
DTE Energy Co. 4.1%
Ameren Corp. 3.8%
Dominion Energy, Inc. 3.8%
Southern Co. 3.7%
C000006638 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Utilities Fund
Class Name Class C
Trading Symbol MMUCX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Utilities Fund for the period of November 1, 2025 to April 30, 2026.
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 $90 1.74%
Expenses Paid, Amount $ 90
Expense Ratio, Percent 1.74%
Net Assets $ 2,817,509,483
Holdings Count | Holding 36
Investment Company Portfolio Turnover 6.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 2,817,509,483 Portfolio Turnover Rate (%): 6
Total Number of Holdings: 36
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 4/30/26)
Portfolio structure
Equities 99.2%
Money Market Funds 0.8%
Top ten holdings
NextEra Energy, Inc. 13.3%
Constellation Energy 7.0%
PG&E Corp. 5.6%
Xcel Energy, Inc. 5.4%
Sempra 4.9%
American Electric Power Co., Inc. 4.9%
DTE Energy Co. 4.1%
Ameren Corp. 3.8%
Dominion Energy, Inc. 3.8%
Southern Co. 3.7%
Industry allocation
Utilities 98.1%
Energy - Renewables 1.9%
Largest Holdings [Text Block]
Top ten holdings
NextEra Energy, Inc. 13.3%
Constellation Energy 7.0%
PG&E Corp. 5.6%
Xcel Energy, Inc. 5.4%
Sempra 4.9%
American Electric Power Co., Inc. 4.9%
DTE Energy Co. 4.1%
Ameren Corp. 3.8%
Dominion Energy, Inc. 3.8%
Southern Co. 3.7%
C000006641 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Utilities Fund
Class Name Class R1
Trading Symbol MMUGX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Utilities Fund for the period of November 1, 2025 to April 30, 2026.
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 $90 1.74%
Expenses Paid, Amount $ 90
Expense Ratio, Percent 1.74%
Net Assets $ 2,817,509,483
Holdings Count | Holding 36
Investment Company Portfolio Turnover 6.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 2,817,509,483 Portfolio Turnover Rate (%): 6
Total Number of Holdings: 36
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 4/30/26)
Portfolio structure
Equities 99.2%
Money Market Funds 0.8%
Top ten holdings
NextEra Energy, Inc. 13.3%
Constellation Energy 7.0%
PG&E Corp. 5.6%
Xcel Energy, Inc. 5.4%
Sempra 4.9%
American Electric Power Co., Inc. 4.9%
DTE Energy Co. 4.1%
Ameren Corp. 3.8%
Dominion Energy, Inc. 3.8%
Southern Co. 3.7%
Industry allocation
Utilities 98.1%
Energy - Renewables 1.9%
Largest Holdings [Text Block]
Top ten holdings
NextEra Energy, Inc. 13.3%
Constellation Energy 7.0%
PG&E Corp. 5.6%
Xcel Energy, Inc. 5.4%
Sempra 4.9%
American Electric Power Co., Inc. 4.9%
DTE Energy Co. 4.1%
Ameren Corp. 3.8%
Dominion Energy, Inc. 3.8%
Southern Co. 3.7%
C000006637 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Utilities Fund
Class Name Class B
Trading Symbol MMUBX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Utilities Fund for the period of November 1, 2025 to April 30, 2026.
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 $90 1.74%
Expenses Paid, Amount $ 90
Expense Ratio, Percent 1.74%
Net Assets $ 2,817,509,483
Holdings Count | Holding 36
Investment Company Portfolio Turnover 6.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 2,817,509,483 Portfolio Turnover Rate (%): 6
Total Number of Holdings: 36
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 4/30/26)
Portfolio structure
Equities 99.2%
Money Market Funds 0.8%
Top ten holdings
NextEra Energy, Inc. 13.3%
Constellation Energy 7.0%
PG&E Corp. 5.6%
Xcel Energy, Inc. 5.4%
Sempra 4.9%
American Electric Power Co., Inc. 4.9%
DTE Energy Co. 4.1%
Ameren Corp. 3.8%
Dominion Energy, Inc. 3.8%
Southern Co. 3.7%
Industry allocation
Utilities 98.1%
Energy - Renewables 1.9%
Largest Holdings [Text Block]
Top ten holdings
NextEra Energy, Inc. 13.3%
Constellation Energy 7.0%
PG&E Corp. 5.6%
Xcel Energy, Inc. 5.4%
Sempra 4.9%
American Electric Power Co., Inc. 4.9%
DTE Energy Co. 4.1%
Ameren Corp. 3.8%
Dominion Energy, Inc. 3.8%
Southern Co. 3.7%
C000006635 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Utilities Fund
Class Name Class A
Trading Symbol MMUFX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Utilities Fund for the period of November 1, 2025 to April 30, 2026.
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 $52 0.99%
Expenses Paid, Amount $ 52
Expense Ratio, Percent 0.99%
Net Assets $ 2,817,509,483
Holdings Count | Holding 36
Investment Company Portfolio Turnover 6.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 4/30/26
Net Assets ($): 2,817,509,483 Portfolio Turnover Rate (%): 6
Total Number of Holdings: 36
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 4/30/26)
Portfolio structure
Equities 99.2%
Money Market Funds 0.8%
Top ten holdings
NextEra Energy, Inc. 13.3%
Constellation Energy 7.0%
PG&E Corp. 5.6%
Xcel Energy, Inc. 5.4%
Sempra 4.9%
American Electric Power Co., Inc. 4.9%
DTE Energy Co. 4.1%
Ameren Corp. 3.8%
Dominion Energy, Inc. 3.8%
Southern Co. 3.7%
Industry allocation
Utilities 98.1%
Energy - Renewables 1.9%
Largest Holdings [Text Block]
Top ten holdings
NextEra Energy, Inc. 13.3%
Constellation Energy 7.0%
PG&E Corp. 5.6%
Xcel Energy, Inc. 5.4%
Sempra 4.9%
American Electric Power Co., Inc. 4.9%
DTE Energy Co. 4.1%
Ameren Corp. 3.8%
Dominion Energy, Inc. 3.8%
Southern Co. 3.7%