| Form N-CSR Cover | 12 Months Ended |
| Dec. 31, 2024 | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSR |
| Amendment Flag | false |
| Registrant Name | BERKSHIRE FUNDS |
| Entity Central Index Key | 0001030979 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Dec. 31, 2024 |
| Shareholder Report | 12 Months Ended |
| Dec. 31, 2024 USD ($) Holding | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSR |
| Amendment Flag | false |
| Registrant Name | BERKSHIRE FUNDS |
| Entity Central Index Key | 0001030979 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Dec. 31, 2024 |
| Berkshire Focus Fund | |
| Shareholder Report [Line Items] | |
| Fund Name | BERKSHIRE FOCUS FUND |
| Class Name | Berkshire Focus Fund |
| Trading Symbol | BFOCX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at www.berkshirefunds.com. 1-877-526-0707 |
| Additional Information Phone Number | 1-877-526-0707 |
| Additional Information Website | www.berkshirefunds.com. |
| Expenses [Text Block] | Fund Costs (based on hypothetical $10,000 investment) Fund Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Berkshire Focus Fund $253.97 1.96% |
| Expenses Paid, Amount | $ 253.97 |
| Expense Ratio, Percent | 1.96% |
| Factors Affecting Performance [Text Block] | Management’s Discussion of Performance For the twelve-month period ended December 31, 2024, the Berkshire Focus Fund significantly outperformed its primary benchmark index. The Fund generated a total return of 59.16% while the S&P 500 ® ® U.S. equity markets delivered another extraordinary performance in 2024, building on the strong returns of the previous year. The S&P 500 ® Our investments in NVIDIA (NVDA), Broadcom (AVGO), Carvana (CVNA), Marvell (MRVL), Meta (META), MicroStrategy (MSTR), Tesla (TSLA) and Taiwan Semiconductor (TSM) were all contributors to the Fund’s performance during the period. However, some of our investments detracted from the Fund’s performance—these included Advanced Micro Devices (AMD), ASML (ASML), MongoDB (MDB) and Western Digital (WDC). New significant additions to the portfolio in the second half were AppLovin (APP), Astera Labs (ALAB), Credo Technology (CRDO), Reddit (RDDT), Robinhood (HOOD), Palantir (PLTR) and Vertiv (VRT). |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | |
| Net Assets | $ 276,400,000 |
| Holdings Count | Holding | 22 |
| Advisory Fees Paid, Amount | $ 3,638,688 |
| Investment Company, Portfolio Turnover | 2,481.80% |
| Additional Fund Statistics [Text Block] | Fund Statistics Net Assets: $ 276.4 Portfolio Holdings: 22 Portfolio Turnover: 2481.8% Total Advisory Fees Paid: $ 3,638,688 |
| Updated Prospectus Web Address | www.berkshirefunds.com. |
| Shareholder Report, Line Graph (Details) - USD ($) | 12 Months Ended | 60 Months Ended | 120 Months Ended | |||||||||||
| Dec. 31, 2024 | Dec. 31, 2024 | 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 | Dec. 31, 2015 | Dec. 31, 2014 | ||
| Berkshire Focus Fund | ||||||||||||||
| Account Value [Line Items] | ||||||||||||||
| Account Value | [1] | $ 39,874 | $ 39,874 | $ 39,874 | $ 24,402 | $ 16,364 | $ 50,813 | $ 48,421 | $ 25,550 | $ 18,182 | $ 16,651 | $ 11,579 | $ 11,005 | $ 9,569 |
| Average Annual Return, Percent | [1] | 59.16% | 9.63% | 14.83% | ||||||||||
| S&P 500® Index | ||||||||||||||
| Account Value [Line Items] | ||||||||||||||
| Account Value | [1] | $ 34,254 | $ 34,254 | $ 34,254 | $ 27,177 | $ 22,201 | $ 26,220 | $ 20,383 | $ 17,129 | $ 13,301 | $ 14,067 | $ 11,292 | $ 9,952 | $ 9,665 |
| Average Annual Return, Percent | [1] | 25.02% | 14.53% | 13.10% | ||||||||||
| [1]The Fund’s past performance is not a good predictor of the Fund’s future performance . | ||||||||||||||
| Shareholder Report, Holdings (Details) - Berkshire Focus Fund | Dec. 31, 2024 |
| NVIDIA Corp. | |
| Holdings [Line Items] | |
| Percent of Total Investments | 14.11% |
| Tesla, Inc. | |
| Holdings [Line Items] | |
| Percent of Total Investments | 6.91% |
| Amazon.com, Inc. | |
| Holdings [Line Items] | |
| Percent of Total Investments | 6.34% |
| Taiwan Semiconductor Mfg. Co. Ltd. – ADR | |
| Holdings [Line Items] | |
| Percent of Total Investments | 6.03% |
| Broadcom, Inc. | |
| Holdings [Line Items] | |
| Percent of Total Investments | 6.02% |
| Astera Labs, Inc. | |
| Holdings [Line Items] | |
| Percent of Total Investments | 5.82% |
| Meta Platforms, Inc. | |
| Holdings [Line Items] | |
| Percent of Total Investments | 4.77% |
| Robinhood Markets, Inc. | |
| Holdings [Line Items] | |
| Percent of Total Investments | 4.70% |
| AppLovin Corp. | |
| Holdings [Line Items] | |
| Percent of Total Investments | 4.17% |
| Affirm Holdings, Inc. | |
| Holdings [Line Items] | |
| Percent of Total Investments | 3.91% |
| Semiconductors | |
| Holdings [Line Items] | |
| Percent of Total Investments | 29.21% |
| Business Software & Services | |
| Holdings [Line Items] | |
| Percent of Total Investments | 14.87% |
| Communication Equipment | |
| Holdings [Line Items] | |
| Percent of Total Investments | 13.93% |
| Internet Services | |
| Holdings [Line Items] | |
| Percent of Total Investments | 9.40% |
| Internet Social Media | |
| Holdings [Line Items] | |
| Percent of Total Investments | 7.79% |
| IT Financial Services | |
| Holdings [Line Items] | |
| Percent of Total Investments | 7.37% |
| Automobile Manufacturers | |
| Holdings [Line Items] | |
| Percent of Total Investments | 6.91% |
| Capital Markets | |
| Holdings [Line Items] | |
| Percent of Total Investments | 4.70% |
| Electrical Equipment | |
| Holdings [Line Items] | |
| Percent of Total Investments | 3.01% |
| Cybersecurity Equipment & Services | |
| Holdings [Line Items] | |
| Percent of Total Investments | 2.94% |
| Semiconductor Equipment | |
| Holdings [Line Items] | |
| Percent of Total Investments | 0.01% |
