Average Annual Total Returns - BRUCE FUND |
12 Months Ended | 60 Months Ended | 120 Months Ended |
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2025 |
Dec. 31, 2025 |
|
| S&P 500 Stock Index (reflects no deduction for fees) | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 17.88% | 14.42% | 14.82% |
| BRUCE FUND | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Label [Optional Text] | Return Before Taxes | ||
| Average Annual Return, Percent | 14.88% | 5.01% | 7.01% |
| BRUCE FUND | After Taxes on Distributions | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 13.12% | 3.05% | 5.42% |
| BRUCE FUND | After Taxes on Distributions and Sales | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 9.87% | 3.63% | 5.31% |