v3.25.1
Shareholder Report
 6 Months Ended
Mar. 31, 2025
USD ($)
Holding
Shareholder Report [Line Items]  
Document Type N-CSRS
Amendment Flag false
Registrant Name MFS SERIES TRUST V
Entity Central Index Key 0000200489
Entity Investment Company Type N-1A
Document Period End Date Mar. 31, 2025
C000006520 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® International New Discovery Fund
Class Name Class A
Trading Symbol MIDAX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS International New Discovery Fund for the period of October 1, 2024 to March 31, 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 $61 1.28%
Expenses Paid, Amount $ 61
Expense Ratio, Percent 1.28%
Net Assets $ 5,923,738,558
Holdings Count | Holding 345
Investment Company Portfolio Turnover 5.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 5,923,738,558 Portfolio Turnover Rate (%): 5
Total Number of Holdings: 345
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 3/31/25)
Portfolio structure
Equities 97.6%
Money Market Funds 2.4%
Issuer country weightings
Japan 27.6%
United Kingdom 11.0%
Australia 5.8%
Germany 4.9%
India 4.3%
France 4.2%
Taiwan 4.0%
Canada 3.8%
China 3.8%
Other Countries 30.6%
Top ten holdings
Dollarama, Inc. 1.5%
OBIC Co. Ltd. 1.3%
Symrise AG 1.2%
Agnico Eagle Mines Ltd. 1.2%
NS Solutions Corp. 1.1%
Breedon Group PLC 1.0%
Cellnex Telecom S.A. 1.0%
GEA Group AG 0.9%
Cranswick PLC 0.9%
Sodexo 0.8%
Largest Holdings [Text Block]
Top ten holdings
Dollarama, Inc. 1.5%
OBIC Co. Ltd. 1.3%
Symrise AG 1.2%
Agnico Eagle Mines Ltd. 1.2%
NS Solutions Corp. 1.1%
Breedon Group PLC 1.0%
Cellnex Telecom S.A. 1.0%
GEA Group AG 0.9%
Cranswick PLC 0.9%
Sodexo 0.8%
C000006525 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® International New Discovery Fund
Class Name Class B
Trading Symbol MIDBX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS International New Discovery Fund for the period of October 1, 2024 to March 31, 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 $97 2.03%
Expenses Paid, Amount $ 97
Expense Ratio, Percent 2.03%
Net Assets $ 5,923,738,558
Holdings Count | Holding 345
Investment Company Portfolio Turnover 5.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 5,923,738,558 Portfolio Turnover Rate (%): 5
Total Number of Holdings: 345
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 3/31/25)
Portfolio structure
Equities 97.6%
Money Market Funds 2.4%
Issuer country weightings
Japan 27.6%
United Kingdom 11.0%
Australia 5.8%
Germany 4.9%
India 4.3%
France 4.2%
Taiwan 4.0%
Canada 3.8%
China 3.8%
Other Countries 30.6%
Top ten holdings
Dollarama, Inc. 1.5%
OBIC Co. Ltd. 1.3%
Symrise AG 1.2%
Agnico Eagle Mines Ltd. 1.2%
NS Solutions Corp. 1.1%
Breedon Group PLC 1.0%
Cellnex Telecom S.A. 1.0%
GEA Group AG 0.9%
Cranswick PLC 0.9%
Sodexo 0.8%
Largest Holdings [Text Block]
Top ten holdings
Dollarama, Inc. 1.5%
OBIC Co. Ltd. 1.3%
Symrise AG 1.2%
Agnico Eagle Mines Ltd. 1.2%
NS Solutions Corp. 1.1%
Breedon Group PLC 1.0%
Cellnex Telecom S.A. 1.0%
GEA Group AG 0.9%
Cranswick PLC 0.9%
Sodexo 0.8%
C000006526 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® International New Discovery Fund
Class Name Class C
Trading Symbol MIDCX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS International New Discovery Fund for the period of October 1, 2024 to March 31, 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 $97 2.03%
Expenses Paid, Amount $ 97
Expense Ratio, Percent 2.03%
Net Assets $ 5,923,738,558
Holdings Count | Holding 345
Investment Company Portfolio Turnover 5.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 5,923,738,558 Portfolio Turnover Rate (%): 5
Total Number of Holdings: 345
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 3/31/25)
Portfolio structure
Equities 97.6%
Money Market Funds 2.4%
Issuer country weightings
Japan 27.6%
United Kingdom 11.0%
Australia 5.8%
Germany 4.9%
India 4.3%
France 4.2%
Taiwan 4.0%
Canada 3.8%
China 3.8%
Other Countries 30.6%
Top ten holdings
Dollarama, Inc. 1.5%
OBIC Co. Ltd. 1.3%
Symrise AG 1.2%
Agnico Eagle Mines Ltd. 1.2%
NS Solutions Corp. 1.1%
Breedon Group PLC 1.0%
Cellnex Telecom S.A. 1.0%
GEA Group AG 0.9%
Cranswick PLC 0.9%
Sodexo 0.8%
Largest Holdings [Text Block]
Top ten holdings
Dollarama, Inc. 1.5%
OBIC Co. Ltd. 1.3%
Symrise AG 1.2%
Agnico Eagle Mines Ltd. 1.2%
NS Solutions Corp. 1.1%
Breedon Group PLC 1.0%
Cellnex Telecom S.A. 1.0%
GEA Group AG 0.9%
Cranswick PLC 0.9%
Sodexo 0.8%
C000006527 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® International New Discovery Fund
Class Name Class I
Trading Symbol MWNIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS International New Discovery Fund for the period of October 1, 2024 to March 31, 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 $49 1.03%
Expenses Paid, Amount $ 49
Expense Ratio, Percent 1.03%
Net Assets $ 5,923,738,558
Holdings Count | Holding 345
Investment Company Portfolio Turnover 5.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 5,923,738,558 Portfolio Turnover Rate (%): 5
Total Number of Holdings: 345
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 3/31/25)
Portfolio structure
Equities 97.6%
Money Market Funds 2.4%
Issuer country weightings
Japan 27.6%
United Kingdom 11.0%
Australia 5.8%
Germany 4.9%
India 4.3%
France 4.2%
Taiwan 4.0%
Canada 3.8%
China 3.8%
Other Countries 30.6%
Top ten holdings
Dollarama, Inc. 1.5%
OBIC Co. Ltd. 1.3%
Symrise AG 1.2%
Agnico Eagle Mines Ltd. 1.2%
NS Solutions Corp. 1.1%
Breedon Group PLC 1.0%
Cellnex Telecom S.A. 1.0%
GEA Group AG 0.9%
Cranswick PLC 0.9%
Sodexo 0.8%
Largest Holdings [Text Block]
Top ten holdings
Dollarama, Inc. 1.5%
OBIC Co. Ltd. 1.3%
Symrise AG 1.2%
Agnico Eagle Mines Ltd. 1.2%
NS Solutions Corp. 1.1%
Breedon Group PLC 1.0%
Cellnex Telecom S.A. 1.0%
GEA Group AG 0.9%
Cranswick PLC 0.9%
Sodexo 0.8%
C000006529 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® International New Discovery Fund
Class Name Class R1
Trading Symbol MIDGX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS International New Discovery Fund for the period of October 1, 2024 to March 31, 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 $97 2.03%
Expenses Paid, Amount $ 97
Expense Ratio, Percent 2.03%
Net Assets $ 5,923,738,558
Holdings Count | Holding 345
Investment Company Portfolio Turnover 5.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 5,923,738,558 Portfolio Turnover Rate (%): 5
Total Number of Holdings: 345
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 3/31/25)
Portfolio structure
Equities 97.6%
Money Market Funds 2.4%
Issuer country weightings
Japan 27.6%
United Kingdom 11.0%
Australia 5.8%
Germany 4.9%
India 4.3%
France 4.2%
Taiwan 4.0%
Canada 3.8%
China 3.8%
Other Countries 30.6%
Top ten holdings
Dollarama, Inc. 1.5%
OBIC Co. Ltd. 1.3%
Symrise AG 1.2%
Agnico Eagle Mines Ltd. 1.2%
NS Solutions Corp. 1.1%
Breedon Group PLC 1.0%
Cellnex Telecom S.A. 1.0%
GEA Group AG 0.9%
Cranswick PLC 0.9%
Sodexo 0.8%
Largest Holdings [Text Block]
Top ten holdings
Dollarama, Inc. 1.5%
OBIC Co. Ltd. 1.3%
Symrise AG 1.2%
Agnico Eagle Mines Ltd. 1.2%
NS Solutions Corp. 1.1%
Breedon Group PLC 1.0%
Cellnex Telecom S.A. 1.0%
GEA Group AG 0.9%
Cranswick PLC 0.9%
Sodexo 0.8%
C000006531 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® International New Discovery Fund
Class Name Class R2
Trading Symbol MIDRX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS International New Discovery Fund for the period of October 1, 2024 to March 31, 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 $73 1.53%
Expenses Paid, Amount $ 73
Expense Ratio, Percent 1.53%
Net Assets $ 5,923,738,558
Holdings Count | Holding 345
Investment Company Portfolio Turnover 5.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 5,923,738,558 Portfolio Turnover Rate (%): 5
Total Number of Holdings: 345
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 3/31/25)
Portfolio structure
Equities 97.6%
Money Market Funds 2.4%
Issuer country weightings
Japan 27.6%
United Kingdom 11.0%
Australia 5.8%
Germany 4.9%
India 4.3%
France 4.2%
Taiwan 4.0%
Canada 3.8%
China 3.8%
Other Countries 30.6%
Top ten holdings
Dollarama, Inc. 1.5%
OBIC Co. Ltd. 1.3%
Symrise AG 1.2%
Agnico Eagle Mines Ltd. 1.2%
NS Solutions Corp. 1.1%
Breedon Group PLC 1.0%
Cellnex Telecom S.A. 1.0%
GEA Group AG 0.9%
Cranswick PLC 0.9%
Sodexo 0.8%
Largest Holdings [Text Block]
Top ten holdings
Dollarama, Inc. 1.5%
OBIC Co. Ltd. 1.3%
Symrise AG 1.2%
Agnico Eagle Mines Ltd. 1.2%
NS Solutions Corp. 1.1%
Breedon Group PLC 1.0%
Cellnex Telecom S.A. 1.0%
GEA Group AG 0.9%
Cranswick PLC 0.9%
Sodexo 0.8%
C000006532 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® International New Discovery Fund
Class Name Class R3
Trading Symbol MIDHX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS International New Discovery Fund for the period of October 1, 2024 to March 31, 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 $61 1.28%
Expenses Paid, Amount $ 61
Expense Ratio, Percent 1.28%
Net Assets $ 5,923,738,558
Holdings Count | Holding 345
Investment Company Portfolio Turnover 5.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 5,923,738,558 Portfolio Turnover Rate (%): 5
Total Number of Holdings: 345
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 3/31/25)
Portfolio structure
Equities 97.6%
Money Market Funds 2.4%
Issuer country weightings
Japan 27.6%
United Kingdom 11.0%
Australia 5.8%
Germany 4.9%
India 4.3%
France 4.2%
Taiwan 4.0%
Canada 3.8%
China 3.8%
Other Countries 30.6%
Top ten holdings
Dollarama, Inc. 1.5%
OBIC Co. Ltd. 1.3%
Symrise AG 1.2%
Agnico Eagle Mines Ltd. 1.2%
NS Solutions Corp. 1.1%
Breedon Group PLC 1.0%
Cellnex Telecom S.A. 1.0%
GEA Group AG 0.9%
Cranswick PLC 0.9%
Sodexo 0.8%
Largest Holdings [Text Block]
Top ten holdings
Dollarama, Inc. 1.5%
OBIC Co. Ltd. 1.3%
Symrise AG 1.2%
Agnico Eagle Mines Ltd. 1.2%
NS Solutions Corp. 1.1%
Breedon Group PLC 1.0%
Cellnex Telecom S.A. 1.0%
GEA Group AG 0.9%
Cranswick PLC 0.9%
Sodexo 0.8%
C000006521 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® International New Discovery Fund
Class Name Class R4
Trading Symbol MIDJX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS International New Discovery Fund for the period of October 1, 2024 to March 31, 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 $49 1.03%
Expenses Paid, Amount $ 49
Expense Ratio, Percent 1.03%
Net Assets $ 5,923,738,558
Holdings Count | Holding 345
Investment Company Portfolio Turnover 5.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 5,923,738,558 Portfolio Turnover Rate (%): 5
Total Number of Holdings: 345
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 3/31/25)
Portfolio structure
Equities 97.6%
Money Market Funds 2.4%
Issuer country weightings
Japan 27.6%
United Kingdom 11.0%
Australia 5.8%
Germany 4.9%
India 4.3%
France 4.2%
Taiwan 4.0%
Canada 3.8%
China 3.8%
Other Countries 30.6%
Top ten holdings
Dollarama, Inc. 1.5%
OBIC Co. Ltd. 1.3%
Symrise AG 1.2%
Agnico Eagle Mines Ltd. 1.2%
NS Solutions Corp. 1.1%
Breedon Group PLC 1.0%
Cellnex Telecom S.A. 1.0%
GEA Group AG 0.9%
Cranswick PLC 0.9%
Sodexo 0.8%
Largest Holdings [Text Block]
Top ten holdings
Dollarama, Inc. 1.5%
OBIC Co. Ltd. 1.3%
Symrise AG 1.2%
Agnico Eagle Mines Ltd. 1.2%
NS Solutions Corp. 1.1%
Breedon Group PLC 1.0%
Cellnex Telecom S.A. 1.0%
GEA Group AG 0.9%
Cranswick PLC 0.9%
Sodexo 0.8%
C000116933 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® International New Discovery Fund
Class Name Class R6
Trading Symbol MIDLX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS International New Discovery Fund for the period of October 1, 2024 to March 31, 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 0.91%
Expenses Paid, Amount $ 44
Expense Ratio, Percent 0.91%
Net Assets $ 5,923,738,558
Holdings Count | Holding 345
Investment Company Portfolio Turnover 5.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 5,923,738,558 Portfolio Turnover Rate (%): 5
Total Number of Holdings: 345
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 3/31/25)
Portfolio structure
Equities 97.6%
Money Market Funds 2.4%
Issuer country weightings
Japan 27.6%
United Kingdom 11.0%
Australia 5.8%
Germany 4.9%
India 4.3%
France 4.2%
Taiwan 4.0%
Canada 3.8%
China 3.8%
Other Countries 30.6%
Top ten holdings
Dollarama, Inc. 1.5%
OBIC Co. Ltd. 1.3%
Symrise AG 1.2%
Agnico Eagle Mines Ltd. 1.2%
NS Solutions Corp. 1.1%
Breedon Group PLC 1.0%
Cellnex Telecom S.A. 1.0%
GEA Group AG 0.9%
Cranswick PLC 0.9%
Sodexo 0.8%
Largest Holdings [Text Block]
Top ten holdings
Dollarama, Inc. 1.5%
OBIC Co. Ltd. 1.3%
Symrise AG 1.2%
Agnico Eagle Mines Ltd. 1.2%
NS Solutions Corp. 1.1%
Breedon Group PLC 1.0%
Cellnex Telecom S.A. 1.0%
GEA Group AG 0.9%
Cranswick PLC 0.9%
Sodexo 0.8%
C000006533 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Research Fund
Class Name Class A
Trading Symbol MFRFX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Research Fund for the period of October 1, 2024 to March 31, 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 $37 0.76%
Expenses Paid, Amount $ 37
Expense Ratio, Percent 0.76%
Net Assets $ 7,441,358,927
Holdings Count | Holding 107
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 7,441,358,927 Portfolio Turnover Rate (%): 16
Total Number of Holdings: 107
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 3/31/25)
Portfolio structure
Equities 99.6%
Money Market Funds 0.4%
Global equity sectors
Technology 30.3%
Financial Services 14.5%
Capital Goods 12.6%
Health Care 11.9%
Consumer Cyclicals 10.4%
Communication Services 9.5%
Energy 6.4%
Consumer Staples 4.0%
Top ten holdings
Microsoft Corp. 7.4%
Amazon.com, Inc. 4.7%
NVIDIA Corp. 4.5%
Meta Platforms, Inc., "A" 4.1%
Apple, Inc. 3.9%
Visa, Inc., "A" 3.5%
Alphabet, Inc., "A" 2.9%
JPMorgan Chase & Co. 2.5%
Salesforce, Inc. 1.5%
Johnson & Johnson 1.5%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 7.4%
Amazon.com, Inc. 4.7%
NVIDIA Corp. 4.5%
Meta Platforms, Inc., "A" 4.1%
Apple, Inc. 3.9%
Visa, Inc., "A" 3.5%
Alphabet, Inc., "A" 2.9%
JPMorgan Chase & Co. 2.5%
Salesforce, Inc. 1.5%
Johnson & Johnson 1.5%
C000006538 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Research Fund
Class Name Class B
Trading Symbol MFRBX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Research Fund for the period of October 1, 2024 to March 31, 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 $73 1.50%
Expenses Paid, Amount $ 73
Expense Ratio, Percent 1.50%
Net Assets $ 7,441,358,927
Holdings Count | Holding 107
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 7,441,358,927 Portfolio Turnover Rate (%): 16
Total Number of Holdings: 107
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 3/31/25)
Portfolio structure
Equities 99.6%
Money Market Funds 0.4%
Global equity sectors
Technology 30.3%
Financial Services 14.5%
Capital Goods 12.6%
Health Care 11.9%
Consumer Cyclicals 10.4%
Communication Services 9.5%
Energy 6.4%
Consumer Staples 4.0%
Top ten holdings
Microsoft Corp. 7.4%
Amazon.com, Inc. 4.7%
NVIDIA Corp. 4.5%
Meta Platforms, Inc., "A" 4.1%
Apple, Inc. 3.9%
Visa, Inc., "A" 3.5%
Alphabet, Inc., "A" 2.9%
JPMorgan Chase & Co. 2.5%
Salesforce, Inc. 1.5%
Johnson & Johnson 1.5%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 7.4%
Amazon.com, Inc. 4.7%
NVIDIA Corp. 4.5%
Meta Platforms, Inc., "A" 4.1%
Apple, Inc. 3.9%
Visa, Inc., "A" 3.5%
Alphabet, Inc., "A" 2.9%
JPMorgan Chase & Co. 2.5%
Salesforce, Inc. 1.5%
Johnson & Johnson 1.5%
C000006539 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Research Fund
Class Name Class C
Trading Symbol MFRCX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Research Fund for the period of October 1, 2024 to March 31, 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 $74 1.51%
Expenses Paid, Amount $ 74
Expense Ratio, Percent 1.51%
Net Assets $ 7,441,358,927
Holdings Count | Holding 107
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 7,441,358,927 Portfolio Turnover Rate (%): 16
Total Number of Holdings: 107
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 3/31/25)
Portfolio structure
Equities 99.6%
Money Market Funds 0.4%
Global equity sectors
Technology 30.3%
Financial Services 14.5%
Capital Goods 12.6%
Health Care 11.9%
Consumer Cyclicals 10.4%
Communication Services 9.5%
Energy 6.4%
Consumer Staples 4.0%
Top ten holdings
Microsoft Corp. 7.4%
Amazon.com, Inc. 4.7%
NVIDIA Corp. 4.5%
Meta Platforms, Inc., "A" 4.1%
Apple, Inc. 3.9%
Visa, Inc., "A" 3.5%
Alphabet, Inc., "A" 2.9%
JPMorgan Chase & Co. 2.5%
Salesforce, Inc. 1.5%
Johnson & Johnson 1.5%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 7.4%
Amazon.com, Inc. 4.7%
NVIDIA Corp. 4.5%
Meta Platforms, Inc., "A" 4.1%
Apple, Inc. 3.9%
Visa, Inc., "A" 3.5%
Alphabet, Inc., "A" 2.9%
JPMorgan Chase & Co. 2.5%
Salesforce, Inc. 1.5%
Johnson & Johnson 1.5%
C000006540 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Research Fund
Class Name Class I
Trading Symbol MRFIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Research Fund for the period of October 1, 2024 to March 31, 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 $25 0.51%
Expenses Paid, Amount $ 25
Expense Ratio, Percent 0.51%
Net Assets $ 7,441,358,927
Holdings Count | Holding 107
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 7,441,358,927 Portfolio Turnover Rate (%): 16
Total Number of Holdings: 107
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 3/31/25)
Portfolio structure
Equities 99.6%
Money Market Funds 0.4%
Global equity sectors
Technology 30.3%
Financial Services 14.5%
Capital Goods 12.6%
Health Care 11.9%
Consumer Cyclicals 10.4%
Communication Services 9.5%
Energy 6.4%
Consumer Staples 4.0%
Top ten holdings
Microsoft Corp. 7.4%
Amazon.com, Inc. 4.7%
NVIDIA Corp. 4.5%
Meta Platforms, Inc., "A" 4.1%
Apple, Inc. 3.9%
Visa, Inc., "A" 3.5%
Alphabet, Inc., "A" 2.9%
JPMorgan Chase & Co. 2.5%
Salesforce, Inc. 1.5%
Johnson & Johnson 1.5%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 7.4%
Amazon.com, Inc. 4.7%
NVIDIA Corp. 4.5%
Meta Platforms, Inc., "A" 4.1%
Apple, Inc. 3.9%
Visa, Inc., "A" 3.5%
Alphabet, Inc., "A" 2.9%
JPMorgan Chase & Co. 2.5%
Salesforce, Inc. 1.5%
Johnson & Johnson 1.5%
C000006542 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Research Fund
Class Name Class R1
Trading Symbol MFRLX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Research Fund for the period of October 1, 2024 to March 31, 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 $73 1.50%
Expenses Paid, Amount $ 73
Expense Ratio, Percent 1.50%
Net Assets $ 7,441,358,927
Holdings Count | Holding 107
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 7,441,358,927 Portfolio Turnover Rate (%): 16
Total Number of Holdings: 107
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 3/31/25)
Portfolio structure
Equities 99.6%
Money Market Funds 0.4%
Global equity sectors
Technology 30.3%
Financial Services 14.5%
Capital Goods 12.6%
Health Care 11.9%
Consumer Cyclicals 10.4%
Communication Services 9.5%
Energy 6.4%
Consumer Staples 4.0%
Top ten holdings
Microsoft Corp. 7.4%
Amazon.com, Inc. 4.7%
NVIDIA Corp. 4.5%
Meta Platforms, Inc., "A" 4.1%
Apple, Inc. 3.9%
Visa, Inc., "A" 3.5%
Alphabet, Inc., "A" 2.9%
JPMorgan Chase & Co. 2.5%
Salesforce, Inc. 1.5%
Johnson & Johnson 1.5%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 7.4%
Amazon.com, Inc. 4.7%
NVIDIA Corp. 4.5%
Meta Platforms, Inc., "A" 4.1%
Apple, Inc. 3.9%
Visa, Inc., "A" 3.5%
Alphabet, Inc., "A" 2.9%
JPMorgan Chase & Co. 2.5%
Salesforce, Inc. 1.5%
Johnson & Johnson 1.5%
C000006544 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Research Fund
Class Name Class R2
Trading Symbol MSRRX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Research Fund for the period of October 1, 2024 to March 31, 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 $49 1.01%
Expenses Paid, Amount $ 49
Expense Ratio, Percent 1.01%
Net Assets $ 7,441,358,927
Holdings Count | Holding 107
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 7,441,358,927 Portfolio Turnover Rate (%): 16
Total Number of Holdings: 107
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 3/31/25)
Portfolio structure
Equities 99.6%
Money Market Funds 0.4%
Global equity sectors
Technology 30.3%
Financial Services 14.5%
Capital Goods 12.6%
Health Care 11.9%
Consumer Cyclicals 10.4%
Communication Services 9.5%
Energy 6.4%
Consumer Staples 4.0%
Top ten holdings
Microsoft Corp. 7.4%
Amazon.com, Inc. 4.7%
NVIDIA Corp. 4.5%
Meta Platforms, Inc., "A" 4.1%
Apple, Inc. 3.9%
Visa, Inc., "A" 3.5%
Alphabet, Inc., "A" 2.9%
JPMorgan Chase & Co. 2.5%
Salesforce, Inc. 1.5%
Johnson & Johnson 1.5%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 7.4%
Amazon.com, Inc. 4.7%
NVIDIA Corp. 4.5%
Meta Platforms, Inc., "A" 4.1%
Apple, Inc. 3.9%
Visa, Inc., "A" 3.5%
Alphabet, Inc., "A" 2.9%
JPMorgan Chase & Co. 2.5%
Salesforce, Inc. 1.5%
Johnson & Johnson 1.5%
C000006545 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Research Fund
Class Name Class R3
Trading Symbol MFRHX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Research Fund for the period of October 1, 2024 to March 31, 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 $37 0.76%
Expenses Paid, Amount $ 37
Expense Ratio, Percent 0.76%
Net Assets $ 7,441,358,927
Holdings Count | Holding 107
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 7,441,358,927 Portfolio Turnover Rate (%): 16
Total Number of Holdings: 107
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 3/31/25)
Portfolio structure
Equities 99.6%
Money Market Funds 0.4%
Global equity sectors
Technology 30.3%
Financial Services 14.5%
Capital Goods 12.6%
Health Care 11.9%
Consumer Cyclicals 10.4%
Communication Services 9.5%
Energy 6.4%
Consumer Staples 4.0%
Top ten holdings
Microsoft Corp. 7.4%
Amazon.com, Inc. 4.7%
NVIDIA Corp. 4.5%
Meta Platforms, Inc., "A" 4.1%
Apple, Inc. 3.9%
Visa, Inc., "A" 3.5%
Alphabet, Inc., "A" 2.9%
JPMorgan Chase & Co. 2.5%
Salesforce, Inc. 1.5%
Johnson & Johnson 1.5%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 7.4%
Amazon.com, Inc. 4.7%
NVIDIA Corp. 4.5%
Meta Platforms, Inc., "A" 4.1%
Apple, Inc. 3.9%
Visa, Inc., "A" 3.5%
Alphabet, Inc., "A" 2.9%
JPMorgan Chase & Co. 2.5%
Salesforce, Inc. 1.5%
Johnson & Johnson 1.5%
C000006534 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Research Fund
Class Name Class R4
Trading Symbol MFRJX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Research Fund for the period of October 1, 2024 to March 31, 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 $25 0.51%
Expenses Paid, Amount $ 25
Expense Ratio, Percent 0.51%
Net Assets $ 7,441,358,927
Holdings Count | Holding 107
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 7,441,358,927 Portfolio Turnover Rate (%): 16
Total Number of Holdings: 107
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 3/31/25)
Portfolio structure
Equities 99.6%
Money Market Funds 0.4%
Global equity sectors
Technology 30.3%
Financial Services 14.5%
Capital Goods 12.6%
Health Care 11.9%
Consumer Cyclicals 10.4%
Communication Services 9.5%
Energy 6.4%
Consumer Staples 4.0%
Top ten holdings
Microsoft Corp. 7.4%
Amazon.com, Inc. 4.7%
NVIDIA Corp. 4.5%
Meta Platforms, Inc., "A" 4.1%
Apple, Inc. 3.9%
Visa, Inc., "A" 3.5%
Alphabet, Inc., "A" 2.9%
JPMorgan Chase & Co. 2.5%
Salesforce, Inc. 1.5%
Johnson & Johnson 1.5%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 7.4%
Amazon.com, Inc. 4.7%
NVIDIA Corp. 4.5%
Meta Platforms, Inc., "A" 4.1%
Apple, Inc. 3.9%
Visa, Inc., "A" 3.5%
Alphabet, Inc., "A" 2.9%
JPMorgan Chase & Co. 2.5%
Salesforce, Inc. 1.5%
Johnson & Johnson 1.5%
C000034431 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Research Fund
Class Name Class R6
Trading Symbol MFRKX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Research Fund for the period of October 1, 2024 to March 31, 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 0.45%
Expenses Paid, Amount $ 22
Expense Ratio, Percent 0.45%
Net Assets $ 7,441,358,927
Holdings Count | Holding 107
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 7,441,358,927 Portfolio Turnover Rate (%): 16
Total Number of Holdings: 107
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 3/31/25)
Portfolio structure
Equities 99.6%
Money Market Funds 0.4%
Global equity sectors
Technology 30.3%
Financial Services 14.5%
Capital Goods 12.6%
Health Care 11.9%
Consumer Cyclicals 10.4%
Communication Services 9.5%
Energy 6.4%
Consumer Staples 4.0%
Top ten holdings
Microsoft Corp. 7.4%
Amazon.com, Inc. 4.7%
NVIDIA Corp. 4.5%
Meta Platforms, Inc., "A" 4.1%
Apple, Inc. 3.9%
Visa, Inc., "A" 3.5%
Alphabet, Inc., "A" 2.9%
JPMorgan Chase & Co. 2.5%
Salesforce, Inc. 1.5%
Johnson & Johnson 1.5%
Largest Holdings [Text Block]
Top ten holdings
Microsoft Corp. 7.4%
Amazon.com, Inc. 4.7%
NVIDIA Corp. 4.5%
Meta Platforms, Inc., "A" 4.1%
Apple, Inc. 3.9%
Visa, Inc., "A" 3.5%
Alphabet, Inc., "A" 2.9%
JPMorgan Chase & Co. 2.5%
Salesforce, Inc. 1.5%
Johnson & Johnson 1.5%
C000006546 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Total Return Fund
Class Name Class A
Trading Symbol MSFRX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Total Return Fund for the period of October 1, 2024 to March 31, 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 $36 0.72%
Expenses Paid, Amount $ 36
Expense Ratio, Percent 0.72%
Net Assets $ 7,739,128,897
Holdings Count | Holding 986
Investment Company Portfolio Turnover 20.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 7,739,128,897 Portfolio Turnover Rate (%): 20
Total Number of Holdings: 986
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 3/31/25)
Portfolio structure
Equities 60.1%
Fixed Income 38.9%
Money Market Funds 1.0%
Equity sectors
Financials 16.0%
Health Care 10.7%
Industrials 7.9%
Consumer Staples 5.1%
Energy 4.4%
Information Technology 4.1%
Communication Services 4.1%
Utilities 3.3%
Consumer Discretionary 2.4%
Materials 2.1%
Composition including fixed income credit quality
AAA 4.5%
AA 1.6%
A 4.6%
BBB 7.7%
CCC 0.0%
U.S. Government 10.4%
Federal Agencies 10.1%
Not Rated 0.0%
Non-Fixed Income 60.1%
Money Market Funds 1.0%
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.
C000006551 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Total Return Fund
Class Name Class B
Trading Symbol MTRBX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Total Return Fund for the period of October 1, 2024 to March 31, 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 $73 1.47%
Expenses Paid, Amount $ 73
Expense Ratio, Percent 1.47%
Net Assets $ 7,739,128,897
Holdings Count | Holding 986
Investment Company Portfolio Turnover 20.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 7,739,128,897 Portfolio Turnover Rate (%): 20
Total Number of Holdings: 986
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 3/31/25)
Portfolio structure
Equities 60.1%
Fixed Income 38.9%
Money Market Funds 1.0%
Equity sectors
Financials 16.0%
Health Care 10.7%
Industrials 7.9%
Consumer Staples 5.1%
Energy 4.4%
Information Technology 4.1%
Communication Services 4.1%
Utilities 3.3%
Consumer Discretionary 2.4%
Materials 2.1%
Composition including fixed income credit quality
AAA 4.5%
AA 1.6%
A 4.6%
BBB 7.7%
CCC 0.0%
U.S. Government 10.4%
Federal Agencies 10.1%
Not Rated 0.0%
Non-Fixed Income 60.1%
Money Market Funds 1.0%
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.
C000006552 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Total Return Fund
Class Name Class C
Trading Symbol MTRCX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Total Return Fund for the period of October 1, 2024 to March 31, 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 $73 1.47%
Expenses Paid, Amount $ 73
Expense Ratio, Percent 1.47%
Net Assets $ 7,739,128,897
Holdings Count | Holding 986
Investment Company Portfolio Turnover 20.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 7,739,128,897 Portfolio Turnover Rate (%): 20
Total Number of Holdings: 986
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 3/31/25)
Portfolio structure
Equities 60.1%
Fixed Income 38.9%
Money Market Funds 1.0%
Equity sectors
Financials 16.0%
Health Care 10.7%
Industrials 7.9%
Consumer Staples 5.1%
Energy 4.4%
Information Technology 4.1%
Communication Services 4.1%
Utilities 3.3%
Consumer Discretionary 2.4%
Materials 2.1%
Composition including fixed income credit quality
AAA 4.5%
AA 1.6%
A 4.6%
BBB 7.7%
CCC 0.0%
U.S. Government 10.4%
Federal Agencies 10.1%
Not Rated 0.0%
Non-Fixed Income 60.1%
Money Market Funds 1.0%
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.
C000006553 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Total Return Fund
Class Name Class I
Trading Symbol MTRIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Total Return Fund for the period of October 1, 2024 to March 31, 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 $24 0.47%
Expenses Paid, Amount $ 24
Expense Ratio, Percent 0.47%
Net Assets $ 7,739,128,897
Holdings Count | Holding 986
Investment Company Portfolio Turnover 20.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 7,739,128,897 Portfolio Turnover Rate (%): 20
Total Number of Holdings: 986
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 3/31/25)
Portfolio structure
Equities 60.1%
Fixed Income 38.9%
Money Market Funds 1.0%
Equity sectors
Financials 16.0%
Health Care 10.7%
Industrials 7.9%
Consumer Staples 5.1%
Energy 4.4%
Information Technology 4.1%
Communication Services 4.1%
Utilities 3.3%
Consumer Discretionary 2.4%
Materials 2.1%
Composition including fixed income credit quality
AAA 4.5%
AA 1.6%
A 4.6%
BBB 7.7%
CCC 0.0%
U.S. Government 10.4%
Federal Agencies 10.1%
Not Rated 0.0%
Non-Fixed Income 60.1%
Money Market Funds 1.0%
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.
C000006555 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Total Return Fund
Class Name Class R1
Trading Symbol MSFFX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Total Return Fund for the period of October 1, 2024 to March 31, 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 $73 1.47%
Expenses Paid, Amount $ 73
Expense Ratio, Percent 1.47%
Net Assets $ 7,739,128,897
Holdings Count | Holding 986
Investment Company Portfolio Turnover 20.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 7,739,128,897 Portfolio Turnover Rate (%): 20
Total Number of Holdings: 986
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 3/31/25)
Portfolio structure
Equities 60.1%
Fixed Income 38.9%
Money Market Funds 1.0%
Equity sectors
Financials 16.0%
Health Care 10.7%
Industrials 7.9%
Consumer Staples 5.1%
Energy 4.4%
Information Technology 4.1%
Communication Services 4.1%
Utilities 3.3%
Consumer Discretionary 2.4%
Materials 2.1%
Composition including fixed income credit quality
AAA 4.5%
AA 1.6%
A 4.6%
BBB 7.7%
CCC 0.0%
U.S. Government 10.4%
Federal Agencies 10.1%
Not Rated 0.0%
Non-Fixed Income 60.1%
Money Market Funds 1.0%
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.
C000006557 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Total Return Fund
Class Name Class R2
Trading Symbol MTRRX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Total Return Fund for the period of October 1, 2024 to March 31, 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 $48 0.97%
Expenses Paid, Amount $ 48
Expense Ratio, Percent 0.97%
Net Assets $ 7,739,128,897
Holdings Count | Holding 986
Investment Company Portfolio Turnover 20.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 7,739,128,897 Portfolio Turnover Rate (%): 20
Total Number of Holdings: 986
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 3/31/25)
Portfolio structure
Equities 60.1%
Fixed Income 38.9%
Money Market Funds 1.0%
Equity sectors
Financials 16.0%
Health Care 10.7%
Industrials 7.9%
Consumer Staples 5.1%
Energy 4.4%
Information Technology 4.1%
Communication Services 4.1%
Utilities 3.3%
Consumer Discretionary 2.4%
Materials 2.1%
Composition including fixed income credit quality
AAA 4.5%
AA 1.6%
A 4.6%
BBB 7.7%
CCC 0.0%
U.S. Government 10.4%
Federal Agencies 10.1%
Not Rated 0.0%
Non-Fixed Income 60.1%
Money Market Funds 1.0%
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.
C000006558 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Total Return Fund
Class Name Class R3
Trading Symbol MSFHX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Total Return Fund for the period of October 1, 2024 to March 31, 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 $36 0.72%
Expenses Paid, Amount $ 36
Expense Ratio, Percent 0.72%
Net Assets $ 7,739,128,897
Holdings Count | Holding 986
Investment Company Portfolio Turnover 20.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 7,739,128,897 Portfolio Turnover Rate (%): 20
Total Number of Holdings: 986
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 3/31/25)
Portfolio structure
Equities 60.1%
Fixed Income 38.9%
Money Market Funds 1.0%
Equity sectors
Financials 16.0%
Health Care 10.7%
Industrials 7.9%
Consumer Staples 5.1%
Energy 4.4%
Information Technology 4.1%
Communication Services 4.1%
Utilities 3.3%
Consumer Discretionary 2.4%
Materials 2.1%
Composition including fixed income credit quality
AAA 4.5%
AA 1.6%
A 4.6%
BBB 7.7%
CCC 0.0%
U.S. Government 10.4%
Federal Agencies 10.1%
Not Rated 0.0%
Non-Fixed Income 60.1%
Money Market Funds 1.0%
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.
C000006547 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Total Return Fund
Class Name Class R4
Trading Symbol MSFJX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Total Return Fund for the period of October 1, 2024 to March 31, 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 $24 0.47%
Expenses Paid, Amount $ 24
Expense Ratio, Percent 0.47%
Net Assets $ 7,739,128,897
Holdings Count | Holding 986
Investment Company Portfolio Turnover 20.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 7,739,128,897 Portfolio Turnover Rate (%): 20
Total Number of Holdings: 986
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 3/31/25)
Portfolio structure
Equities 60.1%
Fixed Income 38.9%
Money Market Funds 1.0%
Equity sectors
Financials 16.0%
Health Care 10.7%
Industrials 7.9%
Consumer Staples 5.1%
Energy 4.4%
Information Technology 4.1%
Communication Services 4.1%
Utilities 3.3%
Consumer Discretionary 2.4%
Materials 2.1%
Composition including fixed income credit quality
AAA 4.5%
AA 1.6%
A 4.6%
BBB 7.7%
CCC 0.0%
U.S. Government 10.4%
Federal Agencies 10.1%
Not Rated 0.0%
Non-Fixed Income 60.1%
Money Market Funds 1.0%
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.
C000116934 [Member]  
Shareholder Report [Line Items]  
Fund Name MFS® Total Return Fund
Class Name Class R6
Trading Symbol MSFKX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about MFS Total Return Fund for the period of October 1, 2024 to March 31, 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 $20 0.39%
Expenses Paid, Amount $ 20
Expense Ratio, Percent 0.39%
Net Assets $ 7,739,128,897
Holdings Count | Holding 986
Investment Company Portfolio Turnover 20.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 3/31/25
Net Assets ($): 7,739,128,897 Portfolio Turnover Rate (%): 20
Total Number of Holdings: 986
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 3/31/25)
Portfolio structure
Equities 60.1%
Fixed Income 38.9%
Money Market Funds 1.0%
Equity sectors
Financials 16.0%
Health Care 10.7%
Industrials 7.9%
Consumer Staples 5.1%
Energy 4.4%
Information Technology 4.1%
Communication Services 4.1%
Utilities 3.3%
Consumer Discretionary 2.4%
Materials 2.1%
Composition including fixed income credit quality
AAA 4.5%
AA 1.6%
A 4.6%
BBB 7.7%
CCC 0.0%
U.S. Government 10.4%
Federal Agencies 10.1%
Not Rated 0.0%
Non-Fixed Income 60.1%
Money Market Funds 1.0%
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.