BRUCE FUND Stock Market and Geopolitical Risk [Member] Issuer-Specific Changes Risk [Member] Management Risk [Member] Distressed Investment Risk [Member] Liquidity Risk [Member] Interest Rate Risk [Member] Value Risk [Member] Growth Risk [Member] Cash Investments Risk [Member] Small- or Micro-Cap Investing Risk [Member] Government Securities Risk [Member] Maturity Risk [Member] Credit Risk [Member] Foreign Investing Risk [Member] Sector Concentration Risk [Member] Issuer Cybersecurity Risk [Member] Business Continuity Risk [Member] BRUCE FUND S&P 500 Stock Index (reflects no deduction for fees) BRUCE FUND [Default Label]