v3.24.2.u1
Shareholder Report
12 Months Ended
Jun. 30, 2024
USD ($)
Holding
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)

Fund Name
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Bruce Fund
$69
0.69%
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]
Growth of 10K Chart
Bruce Fund
S&P 500® Index
Jun-2014
$10,000
$10,000
Jun-2015
$9,887
$10,742
Jun-2016
$10,750
$11,171
Jun-2017
$11,152
$13,170
Jun-2018
$11,599
$15,064
Jun-2019
$12,621
$16,633
Jun-2020
$12,995
$17,881
Jun-2021
$16,819
$25,175
Jun-2022
$16,019
$22,503
Jun-2023
$15,881
$26,912
Jun-2024
$16,409
$33,521
Average Annual Return [Table Text Block]

Average Annual Total Returns 

1 Year
5 Years
10 Years
Bruce Fund
3.32%
5.39%
5.08%
S&P 500® Index
24.56%
15.05%
12.86%

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.

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 

Net Assets
$399,427,557
Number of Portfolio Holdings
41
Advisory Fee
$2,400,450
Portfolio Turnover
8%
Holdings [Text Block]

Asset Weighting (% of total investments)

Group By Asset Type Chart
Value
Value
Common Stocks
67.4%
Convertible Bonds
1.2%
Money Market Funds
27.9%
U.S. Government & Agencies
3.5%
Material Fund Change [Text Block]

Material Fund Changes

No material changes occurred during the year ended June 30, 2024.