Shareholder Report |
12 Months Ended | ||||||||||||||||||||||||||||||||||||
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Jun. 30, 2024
USD ($)
Holding
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| Shareholder Report [Line Items] | |||||||||||||||||||||||||||||||||||||
| Document Type | N-CSR | ||||||||||||||||||||||||||||||||||||
| Amendment Flag | false | ||||||||||||||||||||||||||||||||||||
| Registrant Name | BRUCE FUND INC | ||||||||||||||||||||||||||||||||||||
| Entity Central Index Key | 0000047071 | ||||||||||||||||||||||||||||||||||||
| Entity Investment Company Type | N-1A | ||||||||||||||||||||||||||||||||||||
| Document Period End Date | Jun. 30, 2024 | ||||||||||||||||||||||||||||||||||||
| C000031584 | |||||||||||||||||||||||||||||||||||||
| Shareholder Report [Line Items] | |||||||||||||||||||||||||||||||||||||
| Fund Name | Bruce Fund | ||||||||||||||||||||||||||||||||||||
| Trading Symbol | BRUFX | ||||||||||||||||||||||||||||||||||||
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about Bruce Fund for the period of July 1, 2023 to June 30, 2024. | ||||||||||||||||||||||||||||||||||||
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.thebrucefund.com/document-library. You can also request this information by contacting us at (800) 872-7823. | ||||||||||||||||||||||||||||||||||||
| Additional Information Phone Number | (800) 872-7823 | ||||||||||||||||||||||||||||||||||||
| Additional Information Website | https://www.thebrucefund.com/document-library | ||||||||||||||||||||||||||||||||||||
| Expenses [Text Block] | What were the Fund’s costs for the last year?(based on a hypothetical $10,000 investment)
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| Expenses Paid, Amount | $ 69 | ||||||||||||||||||||||||||||||||||||
| Expense Ratio, Percent | 0.69% | ||||||||||||||||||||||||||||||||||||
| Performance Past Does Not Indicate Future [Text] | The Fund's past performance is not a good predictor of how the Fund will perform in the future. | ||||||||||||||||||||||||||||||||||||
| Line Graph [Table Text Block] | ![]()
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| Average Annual Return [Table Text Block] | Average Annual Total Returns
The Fund's past performance is not a good predictor of how the Fund will perform in the future. The graph and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
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| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. | ||||||||||||||||||||||||||||||||||||
| Material Change Date | Jun. 30, 2024 | ||||||||||||||||||||||||||||||||||||
| AssetsNet | $ 399,427,557 | ||||||||||||||||||||||||||||||||||||
| Holdings Count | Holding | 41 | ||||||||||||||||||||||||||||||||||||
| Advisory Fees Paid, Amount | $ 2,400,450 | ||||||||||||||||||||||||||||||||||||
| InvestmentCompanyPortfolioTurnover | 8.00% | ||||||||||||||||||||||||||||||||||||
| Additional Fund Statistics [Text Block] | Fund Statistics
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| Holdings [Text Block] | Asset Weighting (% of total investments)![]()
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| Material Fund Change [Text Block] | Material Fund ChangesNo material changes occurred during the year ended June 30, 2024. |
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