Annual Total Returns |
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
Dec. 31, 2022 |
Dec. 31, 2021 |
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|---|---|---|---|---|---|---|---|
| MFS Global High Yield Fund | Class A | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | 8.24% | 8.31% | 12.42% | (10.03%) | 2.71% | 4.04% | 13.99% | (3.10%) | 7.10% | 12.92% |
| MFS High Income Fund | Class A | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | 8.69% | 6.58% | 12.18% | (10.56%) | 3.20% | 4.42% | 14.43% | (3.30%) | 6.13% | 13.38% |
| MFS High Yield Pooled Portfolio | Fund Shares | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | 9.44% | 7.56% | 13.34% | (9.86%) | 4.16% | 5.01% | 15.44% | (2.25%) | 7.30% | 14.49% |
| MFS Municipal High Income Fund | Class A | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | 3.51% | 7.09% | 6.14% | (13.84%) | 5.30% | 3.38% | 9.60% | 2.08% | 7.64% | 1.81% |