XML 67 R54.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Unpaid losses and loss adjustment expenses (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2024
Schedule of liability for unpaid claims and claims adjustment expense | Net liabilities of acquired businesses in 2022 related to the acquisition of Alleghany’s insurance companies in October 2022.
| 2024 |  |  | 2023 |  |  | 2022 |
Balance at the beginning of the year: |  |  |  |  |  |  |  |
Gross liabilities | $ | 111,082 |  |  | $ | 107,472 |  |  | $ | 86,664 |
Reinsurance recoverable on unpaid losses |  | (4,893 | ) |  |  | (5,025 | ) |  |  | (2,960 | )
Net liabilities |  | 106,189 |  |  |  | 102,447 |  |  |  | 83,704 |
Losses and loss adjustment expenses incurred: |  |  |  |  |  |  |  |
Current accident year |  | 57,563 |  |  |  | 59,244 |  |  |  | 59,463 |
Prior accident years |  | (2,322 | ) |  |  | (3,541 | ) |  |  | (2,672 | )
Total |  | 55,241 |  |  |  | 55,703 |  |  |  | 56,791 |
Losses and loss adjustment expenses paid: |  |  |  |  |  |  |  |
Current accident year |  | (24,139 | ) |  |  | (25,184 | ) |  |  | (27,236 | )
Prior accident years |  | (26,436 | ) |  |  | (27,065 | ) |  |  | (23,083 | )
Total |  | (50,575 | ) |  |  | (52,249 | ) |  |  | (50,319 | )
Foreign currency effect |  | (297 | ) |  |  | 288 |  |  |  | (508 | )
Net liabilities of acquired businesses |  | — |  |  |  | — |  |  |  | 12,779 |
Balance at December 31: |  |  |  |  |  |  |  |
Net liabilities |  | 110,558 |  |  |  | 106,189 |  |  |  | 102,447 |
Reinsurance recoverable on unpaid losses |  | 4,593 |  |  |  | 4,893 |  |  |  | 5,025 |
Gross liabilities | $ | 115,151 |  |  | $ | 111,082 |  |  | $ | 107,472 |
Schedule of reconciliation of unpaid losses and allocated loss adjustment expenses to balance sheet liability | A reconciliation of the disaggregated net unpaid losses and allocated loss adjustment expenses (the latter referred to as “ALAE”) to our consolidated claim liabilities as of December 31, 2024 follows (in millions).
| GEICO |  |  | BH Primary |  |  | BHRG |  |  |  |
| Physical Damage |  |  | Auto Liability |  |  | Medical Professional Liability |  |  | Workers’ Compensation/ Other Casualty |  |  | Property |  |  | Casualty |  |  | Total |
Unpaid losses and ALAE, net | $ | 885 |  |  | $ | 20,818 |  |  | $ | 9,432 |  |  | $ | 24,335 |  |  | $ | 15,851 |  |  | $ | 33,350 |  |  | $ | 104,671 |
Reinsurance recoverable |  | 3 |  |  |  | 884 |  |  |  | 29 |  |  |  | 1,473 |  |  |  | 634 |  |  |  | 1,369 |  |  |  | 4,392 |
Unallocated loss adjustment expenses |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,414 |
Other losses and loss adjustment expenses |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3,674 |
Unpaid losses and loss adjustment expenses |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ | 115,151 |
Schedule of average historical claims duration | Required supplemental unaudited average historical claims duration information based on the net losses and ALAE incurred and paid accident year data in the preceding tables follows. The percentages show the average portions of net losses and ALAE paid by each succeeding year, with year 1 representing the current accident year.
Average Annual Percentage Payout of Losses Incurred by Age, Net of Reinsurance
In Year | 1 |  | 2 |  | 3 |  | 4 |  | 5 |  | 6 |  | 7 |  | 8 |  | 9 |  | 10
GEICO Physical Damage | 97% |  | 3% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
GEICO Auto Liability | 41% |  | 31% |  | 13% |  | 7% |  | 4% |  |  |  |  |  |  |  |  |  |
BH Primary Medical Professional Liability | 2% |  | 8% |  | 12% |  | 14% |  | 13% |  | 12% |  | 8% |  | 8% |  | 4% |  | 4%
BH Primary Workers’ Compensation and Other Casualty | 14% |  | 17% |  | 14% |  | 12% |  | 10% |  | 7% |  | 5% |  | 3% |  | 1% |  | 1%
BHRG Property | 22% |  | 35% |  | 15% |  | 8% |  | 4% |  | 4% |  | 2% |  | 1% |  | 2% |  | 2%
BHRG Casualty | 13% |  | 17% |  | 13% |  | 11% |  | 8% |  | 6% |  | 5% |  | 4% |  | 4% |  | 3%
GEICO [Member] | Insurance Group [Member] | Physical Damage [Member] |
Schedule of Losses and allocated loss adjustment expenses Incurred | Physical Damage
|  | Losses and ALAE Incurred through December 31, |  |  |  |  |  | Cumulative Number of |
Accident Year |  |  |  | 2023* |  |  | 2024 |  |  | IBNR and Case Development Liabilities |  |  | Reported Claims (in thousands) |
2023 |  |  |  | $ | 12,273 |  |  | $ | 11,900 |  |  | $ | 111 |  |  |  | 7,430 |
2024 |  |  |  |  |  | 11,095 |  |  |  | (454 | ) |  |  | 6,380 |
|  | Losses and ALAE incurred |  |  | $ | 22,995 |  |  |  |  |  |  |
|  | Cumulative Losses and ALAE Paid through December 31, |  |  |  |  |  |  |
Accident Year |  |  |  | 2023* |  |  | 2024 |  |  |  |  |  |  |
2023 |  |  |  | $ | 11,567 |  |  | $ | 11,771 |  |  |  |  |  |  |
2024 |  |  |  |  |  | 10,495 |  |  |  |  |  |  |
|  | Losses and ALAE paid |  |  |  | 22,266 |  |  |  |  |  |  |
|  | Net unpaid losses and ALAE for 2023 – 2024 accident years |  |  |  | 729 |  |  |  |  |  |  |
|  | Net unpaid losses and ALAE for accident years before 2023 |  |  |  | 156 |  |  |  |  |  |  |
|  | Net unpaid losses and ALAE |  |  | $ | 885 |  |  |  |  |  |  |
GEICO [Member] | Insurance Group [Member] | Auto Liability [Member] |
Schedule of Losses and allocated loss adjustment expenses Incurred | Auto Liability
|  | Losses and ALAE Incurred through December 31, |  |  |  |  |  | Cumulative Number of |
Accident Year |  | 2020* |  |  | 2021* |  |  | 2022* |  |  | 2023* |  |  | 2024 |  |  | IBNR and Case Development Liabilities |  |  | Reported Claims (in thousands) |
2020 |  | $ | 14,637 |  |  | $ | 14,024 |  |  | $ | 13,697 |  |  | $ | 13,593 |  |  | $ | 13,462 |  |  | $ | 382 |  |  |  | 2,127 |
2021 |  |  |  |  |  | 17,481 |  |  |  | 17,457 |  |  |  | 17,229 |  |  |  | 17,033 |  |  |  | 907 |  |  |  | 2,457 |
2022 |  |  |  |  |  |  |  |  | 19,645 |  |  |  | 18,903 |  |  |  | 18,818 |  |  |  | 2,065 |  |  |  | 2,387 |
2023 |  |  |  |  |  |  |  |  |  |  |  | 17,948 |  |  |  | 18,073 |  |  |  | 3,864 |  |  |  | 1,956 |
2024 |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 17,081 |  |  |  | 4,730 |  |  |  | 1,694 |
|  | Losses and ALAE incurred |  |  | $ | 84,467 |  |  |  |  |  |  |
|  | Cumulative Losses and ALAE Paid through December 31, |  |  |  |  |  |  |
Accident Year |  | 2020* |  |  | 2021* |  |  | 2022* |  |  | 2023* |  |  | 2024 |  |  |  |  |  |  |
2020 |  | $ | 5,395 |  |  | $ | 9,839 |  |  | $ | 11,794 |  |  | $ | 12,608 |  |  | $ | 12,946 |  |  |  |  |  |  |
2021 |  |  |  |  |  | 6,450 |  |  |  | 12,681 |  |  |  | 14,863 |  |  |  | 15,796 |  |  |  |  |  |  |
2022 |  |  |  |  |  |  |  |  | 7,614 |  |  |  | 13,838 |  |  |  | 16,031 |  |  |  |  |  |  |
2023 |  |  |  |  |  |  |  |  |  |  |  | 7,191 |  |  |  | 12,682 |  |  |  |  |  |  |
2024 |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7,084 |  |  |  |  |  |  |
|  | Losses and ALAE paid |  |  |  | 64,539 |  |  |  |  |  |  |
|  | Net unpaid losses and ALAE for 2020 – 2024 accident years |  |  |  | 19,928 |  |  |  |  |  |  |
|  | Net unpaid losses and ALAE for accident years before 2020 |  |  |  | 890 |  |  |  |  |  |  |
|  | Net unpaid losses and ALAE |  |  | $ | 20,818 |  |  |  |  |  |  |
* Unaudited required supplemental information
Berkshire Hathaway Primary Group [Member] | Insurance Group [Member] | Medical Professional Liability [Member] |
Schedule of Losses and allocated loss adjustment expenses Incurred | Medical Professional Liability Estimates of the ultimate expected losses and loss adjustment expenses incurred for medical professional claim liabilities are based on a variety of commonly accepted actuarial methodologies, such as the paid and incurred development method and Bornhuetter-Ferguson based methods, as well as other techniques that consider insured loss exposures and historical and expected loss trends, among other factors. These methodologies produce loss estimates from which we determine our best estimate. In addition, we study developments in older accident years and adjust initial loss estimates to reflect recent developments based upon claim age, coverage and litigation experience.
|  | Losses and ALAE Incurred through December 31, |  |  |  |  |  | Cumulative Number of |
Accident Year |  | 2015* |  |  | 2016* |  |  | 2017* |  |  | 2018* |  |  | 2019* |  |  | 2020* |  |  | 2021* |  |  | 2022* |  |  | 2023* |  |  | 2024 |  |  | IBNR and Case Development Liabilities |  |  | Reported Claims (in thousands) |
2015 |  | $ | 1,374 |  |  | $ | 1,342 |  |  | $ | 1,269 |  |  | $ | 1,290 |  |  | $ | 1,218 |  |  | $ | 1,157 |  |  | $ | 1,093 |  |  | $ | 1,033 |  |  | $ | 1,016 |  |  | $ | 1,010 |  |  | $ | 37 |  |  |  | 12 |
2016 |  |  |  |  |  | 1,392 |  |  |  | 1,416 |  |  |  | 1,414 |  |  |  | 1,394 |  |  |  | 1,341 |  |  |  | 1,288 |  |  |  | 1,216 |  |  |  | 1,188 |  |  |  | 1,172 |  |  |  | 78 |  |  |  | 15 |
2017 |  |  |  |  |  |  |  |  | 1,466 |  |  |  | 1,499 |  |  |  | 1,495 |  |  |  | 1,474 |  |  |  | 1,382 |  |  |  | 1,349 |  |  |  | 1,315 |  |  |  | 1,310 |  |  |  | 89 |  |  |  | 21 |
2018 |  |  |  |  |  |  |  |  |  |  |  | 1,602 |  |  |  | 1,650 |  |  |  | 1,659 |  |  |  | 1,580 |  |  |  | 1,616 |  |  |  | 1,606 |  |  |  | 1,583 |  |  |  | 140 |  |  |  | 24 |
2019 |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,670 |  |  |  | 1,691 |  |  |  | 1,663 |  |  |  | 1,614 |  |  |  | 1,534 |  |  |  | 1,579 |  |  |  | 180 |  |  |  | 22 |
2020 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,704 |  |  |  | 1,751 |  |  |  | 1,698 |  |  |  | 1,631 |  |  |  | 1,606 |  |  |  | 369 |  |  |  | 33 |
2021 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,852 |  |  |  | 1,855 |  |  |  | 1,787 |  |  |  | 1,714 |  |  |  | 718 |  |  |  | 27 |
2022 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,927 |  |  |  | 1,912 |  |  |  | 1,846 |  |  |  | 981 |  |  |  | 25 |
2023 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,964 |  |  |  | 1,918 |  |  |  | 1,428 |  |  |  | 27 |
2024 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,004 |  |  |  | 1,793 |  |  |  | 22 |
|  | Losses and ALAE incurred |  |  | $ | 15,742 |  |  |  |  |  |  |
|  | Cumulative Losses and ALAE Paid through December 31, |  |  |  |  |  |  |
Accident Year |  | 2015* |  |  | 2016* |  |  | 2017* |  |  | 2018* |  |  | 2019* |  |  | 2020* |  |  | 2021* |  |  | 2022* |  |  | 2023* |  |  | 2024 |  |  |  |  |  |  |
2015 |  | $ | 23 |  |  | $ | 108 |  |  | $ | 218 |  |  | $ | 382 |  |  | $ | 543 |  |  | $ | 663 |  |  | $ | 719 |  |  | $ | 799 |  |  | $ | 843 |  |  | $ | 879 |  |  |  |  |  |  |
2016 |  |  |  |  |  | 22 |  |  |  | 115 |  |  |  | 274 |  |  |  | 461 |  |  |  | 620 |  |  |  | 712 |  |  |  | 822 |  |  |  | 908 |  |  |  | 957 |  |  |  |  |  |  |
2017 |  |  |  |  |  |  |  |  | 27 |  |  |  | 128 |  |  |  | 300 |  |  |  | 457 |  |  |  | 582 |  |  |  | 739 |  |  |  | 877 |  |  |  | 977 |  |  |  |  |  |  |
2018 |  |  |  |  |  |  |  |  |  |  |  | 35 |  |  |  | 166 |  |  |  | 367 |  |  |  | 543 |  |  |  | 728 |  |  |  | 949 |  |  |  | 1,080 |  |  |  |  |  |  |
2019 |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 39 |  |  |  | 160 |  |  |  | 314 |  |  |  | 536 |  |  |  | 757 |  |  |  | 963 |  |  |  |  |  |  |
2020 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 34 |  |  |  | 148 |  |  |  | 321 |  |  |  | 531 |  |  |  | 767 |  |  |  |  |  |  |
2021 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 36 |  |  |  | 136 |  |  |  | 333 |  |  |  | 548 |  |  |  |  |  |  |
2022 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 38 |  |  |  | 182 |  |  |  | 441 |  |  |  |  |  |  |
2023 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 28 |  |  |  | 156 |  |  |  |  |  |  |
2024 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 34 |  |  |  |  |  |  |
|  | Losses and ALAE paid |  |  |  | 6,802 |  |  |  |  |  |  |
|  | Net unpaid losses and ALAE for 2015 – 2024 accident years |  |  |  | 8,940 |  |  |  |  |  |  |
|  | Net unpaid losses and ALAE for accident years before 2015 |  |  |  | 492 |  |  |  |  |  |  |
|  | Net unpaid losses and ALAE |  |  | $ | 9,432 |  |  |  |  |  |  |
* Unaudited required supplemental information
Berkshire Hathaway Primary Group [Member] | Insurance Group [Member] | Workers' Compensation and Other Casualty [Member] |
Schedule of Losses and allocated loss adjustment expenses Incurred | Workers’ Compensation and Other Casualty We evaluate ultimate loss and loss adjustment expense estimates for workers’ compensation and other casualty claims using a combination of commonly accepted actuarial methodologies such as the Bornhuetter-Ferguson and chain-ladder approaches using paid and incurred loss data. Paid and incurred loss data is segregated and analyzed by state due to the different state regulatory frameworks that may impact the duration and amount of loss payments. We also separately study the various components of liabilities, such as employee lost wages, medical expenses and the costs of claims investigations and administration. We establish case liabilities for reported claims based upon the facts and circumstances of the claim. The excess of the ultimate projected losses, including the case development estimates over the case-basis liabilities, is included in IBNR liabilities.
|  | Losses and ALAE Incurred through December 31, |  |  |  |  |  | Cumulative Number of |
Accident Year |  | 2015* |  |  | 2016* |  |  | 2017* |  |  | 2018* |  |  | 2019* |  |  | 2020* |  |  | 2021* |  |  | 2022* |  |  | 2023* |  |  | 2024 |  |  | IBNR and Case Development Liabilities |  |  | Reported Claims (in thousands) |
2015 |  | $ | 2,580 |  |  | $ | 2,539 |  |  | $ | 2,455 |  |  | $ | 2,426 |  |  | $ | 2,428 |  |  | $ | 2,402 |  |  | $ | 2,408 |  |  | $ | 2,393 |  |  | $ | 2,358 |  |  | $ | 2,367 |  |  | $ | 178 |  |  |  | 120 |
2016 |  |  |  |  |  | 2,931 |  |  |  | 2,848 |  |  |  | 2,793 |  |  |  | 2,772 |  |  |  | 2,815 |  |  |  | 2,825 |  |  |  | 2,864 |  |  |  | 2,840 |  |  |  | 2,809 |  |  |  | 277 |  |  |  | 125 |
2017 |  |  |  |  |  |  |  |  | 3,473 |  |  |  | 3,337 |  |  |  | 3,299 |  |  |  | 3,310 |  |  |  | 3,322 |  |  |  | 3,320 |  |  |  | 3,321 |  |  |  | 3,357 |  |  |  | 395 |  |  |  | 143 |
2018 |  |  |  |  |  |  |  |  |  |  |  | 3,998 |  |  |  | 3,886 |  |  |  | 3,967 |  |  |  | 4,030 |  |  |  | 4,091 |  |  |  | 4,177 |  |  |  | 4,230 |  |  |  | 570 |  |  |  | 164 |
2019 |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4,584 |  |  |  | 4,623 |  |  |  | 4,692 |  |  |  | 4,763 |  |  |  | 4,847 |  |  |  | 4,919 |  |  |  | 691 |  |  |  | 185 |
2020 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5,030 |  |  |  | 4,881 |  |  |  | 4,775 |  |  |  | 4,774 |  |  |  | 4,866 |  |  |  | 1,167 |  |  |  | 157 |
2021 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5,899 |  |  |  | 5,856 |  |  |  | 5,882 |  |  |  | 5,983 |  |  |  | 1,923 |  |  |  | 318 |
2022 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6,796 |  |  |  | 6,757 |  |  |  | 6,866 |  |  |  | 2,801 |  |  |  | 316 |
2023 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7,299 |  |  |  | 7,363 |  |  |  | 3,887 |  |  |  | 187 |
2024 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7,962 |  |  |  | 5,552 |  |  |  | 169 |
|  | Losses and ALAE incurred |  |  | $ | 50,722 |  |  |  |  |  |  |
|  | Cumulative Losses and ALAE Paid through December 31, |  |  |  |  |  |  |
Accident Year |  | 2015* |  |  | 2016* |  |  | 2017* |  |  | 2018* |  |  | 2019* |  |  | 2020* |  |  | 2021* |  |  | 2022* |  |  | 2023* |  |  | 2024 |  |  |  |  |  |  |
2015 |  | $ | 329 |  |  | $ | 804 |  |  | $ | 1,187 |  |  | $ | 1,507 |  |  | $ | 1,766 |  |  | $ | 1,873 |  |  | $ | 1,966 |  |  | $ | 2,041 |  |  | $ | 2,070 |  |  | $ | 2,095 |  |  |  |  |  |  |
2016 |  |  |  |  |  | 373 |  |  |  | 908 |  |  |  | 1,359 |  |  |  | 1,765 |  |  |  | 1,998 |  |  |  | 2,140 |  |  |  | 2,303 |  |  |  | 2,377 |  |  |  | 2,420 |  |  |  |  |  |  |
2017 |  |  |  |  |  |  |  |  | 480 |  |  |  | 1,133 |  |  |  | 1,645 |  |  |  | 2,050 |  |  |  | 2,279 |  |  |  | 2,492 |  |  |  | 2,673 |  |  |  | 2,784 |  |  |  |  |  |  |
2018 |  |  |  |  |  |  |  |  |  |  |  | 583 |  |  |  | 1,340 |  |  |  | 1,902 |  |  |  | 2,324 |  |  |  | 2,746 |  |  |  | 3,120 |  |  |  | 3,396 |  |  |  |  |  |  |
2019 |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 725 |  |  |  | 1,598 |  |  |  | 2,214 |  |  |  | 2,898 |  |  |  | 3,430 |  |  |  | 3,812 |  |  |  |  |  |  |
2020 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 736 |  |  |  | 1,498 |  |  |  | 2,066 |  |  |  | 2,598 |  |  |  | 3,138 |  |  |  |  |  |  |
2021 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 869 |  |  |  | 1,751 |  |  |  | 2,440 |  |  |  | 3,168 |  |  |  |  |  |  |
2022 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 962 |  |  |  | 2,012 |  |  |  | 2,905 |  |  |  |  |  |  |
2023 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,056 |  |  |  | 2,152 |  |  |  |  |  |  |
2024 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,245 |  |  |  |  |  |  |
|  | Losses and ALAE paid |  |  |  | 27,115 |  |  |  |  |  |  |
|  | Net unpaid losses and ALAE for 2015 – 2024 accident years |  |  |  | 23,607 |  |  |  |  |  |  |
|  | Net unpaid losses and ALAE for accident years before 2015 |  |  |  | 728 |  |  |  |  |  |  |
|  | Net unpaid losses and ALAE |  |  | $ | 24,335 |  |  |  |  |  |  |
* Unaudited required supplemental information
Berkshire Hathaway Reinsurance Group [Member] | Insurance Group [Member] | Property [Member] |
Schedule of Losses and allocated loss adjustment expenses Incurred | IBNR and case development liabilities are as of December 31, 2024. Dollars are in millions. Property
|  | Losses and ALAE Incurred through December 31, |  |  |  |
Accident Year |  | 2015* |  |  | 2016* |  |  | 2017* |  |  | 2018* |  |  | 2019* |  |  | 2020* |  |  | 2021* |  |  | 2022* |  |  | 2023* |  |  | 2024 |  |  | IBNR and Case Development Liabilities |
2015 |  | $ | 3,587 |  |  | $ | 3,392 |  |  | $ | 2,827 |  |  | $ | 3,218 |  |  | $ | 3,214 |  |  | $ | 3,236 |  |  | $ | 3,238 |  |  | $ | 3,232 |  |  | $ | 3,255 |  |  | $ | 3,225 |  |  | $ | 94 |
2016 |  |  |  |  |  | 3,905 |  |  |  | 4,492 |  |  |  | 4,170 |  |  |  | 4,134 |  |  |  | 4,132 |  |  |  | 4,121 |  |  |  | 4,099 |  |  |  | 4,088 |  |  |  | 4,091 |  |  |  | 30 |
2017 |  |  |  |  |  |  |  |  | 6,374 |  |  |  | 6,071 |  |  |  | 5,893 |  |  |  | 5,767 |  |  |  | 5,689 |  |  |  | 5,608 |  |  |  | 5,590 |  |  |  | 5,577 |  |  |  | 51 |
2018 |  |  |  |  |  |  |  |  |  |  |  | 5,456 |  |  |  | 5,542 |  |  |  | 5,402 |  |  |  | 5,260 |  |  |  | 5,267 |  |  |  | 5,218 |  |  |  | 5,238 |  |  |  | 207 |
2019 |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4,951 |  |  |  | 5,064 |  |  |  | 4,838 |  |  |  | 4,537 |  |  |  | 4,488 |  |  |  | 4,447 |  |  |  | 112 |
2020 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6,914 |  |  |  | 7,188 |  |  |  | 6,825 |  |  |  | 6,620 |  |  |  | 6,450 |  |  |  | 376 |
2021 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 8,063 |  |  |  | 7,919 |  |  |  | 7,585 |  |  |  | 7,289 |  |  |  | 450 |
2022 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 8,852 |  |  |  | 8,412 |  |  |  | 7,916 |  |  |  | 1,102 |
2023 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7,953 |  |  |  | 7,379 |  |  |  | 1,632 |
2024 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7,750 |  |  |  | 4,225 |
Losses and ALAE Incurred |  |  | $ | 59,362 |  |  |  |
|  | Cumulative Losses and ALAE Paid through December 31, |  |  |  |
Accident Year |  | 2015* |  |  | 2016* |  |  | 2017* |  |  | 2018* |  |  | 2019* |  |  | 2020* |  |  | 2021* |  |  | 2022* |  |  | 2023* |  |  | 2024 |  |  |  |
2015 |  | $ | 669 |  |  | $ | 1,793 |  |  | $ | 2,196 |  |  | $ | 2,414 |  |  | $ | 2,522 |  |  | $ | 2,705 |  |  | $ | 2,791 |  |  | $ | 2,843 |  |  | $ | 2,917 |  |  | $ | 2,966 |  |  |  |
2016 |  |  |  |  |  | 913 |  |  |  | 2,203 |  |  |  | 2,662 |  |  |  | 3,151 |  |  |  | 3,419 |  |  |  | 3,615 |  |  |  | 3,724 |  |  |  | 3,802 |  |  |  | 3,889 |  |  |  |
2017 |  |  |  |  |  |  |  |  | 1,346 |  |  |  | 3,494 |  |  |  | 4,564 |  |  |  | 4,915 |  |  |  | 5,150 |  |  |  | 5,343 |  |  |  | 5,432 |  |  |  | 5,456 |  |  |  |
2018 |  |  |  |  |  |  |  |  |  |  |  | 1,204 |  |  |  | 3,073 |  |  |  | 3,709 |  |  |  | 3,992 |  |  |  | 4,236 |  |  |  | 4,444 |  |  |  | 4,571 |  |  |  |
2019 |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,009 |  |  |  | 2,826 |  |  |  | 3,532 |  |  |  | 3,856 |  |  |  | 4,018 |  |  |  | 4,082 |  |  |  |
2020 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,252 |  |  |  | 3,569 |  |  |  | 4,613 |  |  |  | 5,275 |  |  |  | 5,546 |  |  |  |
2021 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,621 |  |  |  | 4,070 |  |  |  | 5,377 |  |  |  | 6,073 |  |  |  |
2022 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,813 |  |  |  | 4,322 |  |  |  | 5,588 |  |  |  |
2023 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,771 |  |  |  | 4,107 |  |  |  |
2024 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,720 |  |  |  |
Losses and ALAE Paid |  |  |  | 43,998 |  |  |  |
Net unpaid losses and ALAE for 2015 – 2024 accident years |  |  |  | 15,364 |  |  |  |
Net unpaid losses and ALAE for accident years before 2015 |  |  |  | 487 |  |  |  |
Net unpaid losses and ALAE |  |  | $ | 15,851 |  |  |  |
* Unaudited required supplemental information
Berkshire Hathaway Reinsurance Group [Member] | Insurance Group [Member] | Casualty [Member] |
Schedule of Losses and allocated loss adjustment expenses Incurred | Casualty
|  | Losses and ALAE Incurred through December 31, |  |  |  |
Accident Year |  | 2015* |  |  | 2016* |  |  | 2017* |  |  | 2018* |  |  | 2019* |  |  | 2020* |  |  | 2021* |  |  | 2022* |  |  | 2023* |  |  | 2024 |  |  | IBNR and Case Development Liabilities |
2015 |  | $ | 3,409 |  |  | $ | 3,615 |  |  | $ | 3,655 |  |  | $ | 3,568 |  |  | $ | 3,426 |  |  | $ | 3,388 |  |  | $ | 3,351 |  |  | $ | 3,298 |  |  | $ | 3,300 |  |  | $ | 3,276 |  |  | $ | 311 |
2016 |  |  |  |  |  | 3,777 |  |  |  | 3,987 |  |  |  | 3,891 |  |  |  | 3,859 |  |  |  | 3,808 |  |  |  | 3,765 |  |  |  | 3,735 |  |  |  | 3,763 |  |  |  | 3,793 |  |  |  | 370 |
2017 |  |  |  |  |  |  |  |  | 4,028 |  |  |  | 4,462 |  |  |  | 4,339 |  |  |  | 4,232 |  |  |  | 4,164 |  |  |  | 4,154 |  |  |  | 4,211 |  |  |  | 4,214 |  |  |  | 432 |
2018 |  |  |  |  |  |  |  |  |  |  |  | 4,875 |  |  |  | 5,523 |  |  |  | 5,476 |  |  |  | 5,345 |  |  |  | 5,273 |  |  |  | 5,359 |  |  |  | 5,429 |  |  |  | 647 |
2019 |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5,559 |  |  |  | 6,025 |  |  |  | 5,885 |  |  |  | 5,718 |  |  |  | 5,678 |  |  |  | 5,751 |  |  |  | 1,002 |
2020 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6,203 |  |  |  | 6,215 |  |  |  | 6,033 |  |  |  | 6,079 |  |  |  | 6,053 |  |  |  | 1,371 |
2021 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6,300 |  |  |  | 6,270 |  |  |  | 5,942 |  |  |  | 5,959 |  |  |  | 1,838 |
2022 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6,047 |  |  |  | 6,092 |  |  |  | 6,045 |  |  |  | 2,829 |
2023 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6,053 |  |  |  | 6,144 |  |  |  | 3,528 |
2024 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6,093 |  |  |  | 4,660 |
|  | Losses and ALAE incurred |  |  | $ | 52,757 |  |  |  |
|  | Cumulative Losses and ALAE Paid through December 31, |  |  |  |
Accident Year |  | 2015* |  |  | 2016* |  |  | 2017* |  |  | 2018* |  |  | 2019* |  |  | 2020* |  |  | 2021* |  |  | 2022* |  |  | 2023* |  |  | 2024 |  |  |  |
2015 |  | $ | 445 |  |  | $ | 990 |  |  | $ | 1,425 |  |  | $ | 1,724 |  |  | $ | 1,996 |  |  | $ | 2,190 |  |  | $ | 2,338 |  |  | $ | 2,473 |  |  | $ | 2,582 |  |  | $ | 2,678 |  |  |  |
2016 |  |  |  |  |  | 653 |  |  |  | 1,355 |  |  |  | 1,795 |  |  |  | 2,143 |  |  |  | 2,414 |  |  |  | 2,607 |  |  |  | 2,782 |  |  |  | 2,957 |  |  |  | 3,095 |  |  |  |
2017 |  |  |  |  |  |  |  |  | 605 |  |  |  | 1,306 |  |  |  | 1,823 |  |  |  | 2,472 |  |  |  | 2,720 |  |  |  | 2,938 |  |  |  | 3,164 |  |  |  | 3,350 |  |  |  |
2018 |  |  |  |  |  |  |  |  |  |  |  | 693 |  |  |  | 1,737 |  |  |  | 2,786 |  |  |  | 3,252 |  |  |  | 3,631 |  |  |  | 3,948 |  |  |  | 4,224 |  |  |  |
2019 |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 839 |  |  |  | 1,865 |  |  |  | 2,414 |  |  |  | 3,181 |  |  |  | 3,727 |  |  |  | 4,094 |  |  |  |
2020 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 866 |  |  |  | 1,900 |  |  |  | 2,709 |  |  |  | 3,373 |  |  |  | 3,967 |  |  |  |
2021 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 765 |  |  |  | 1,781 |  |  |  | 2,654 |  |  |  | 3,225 |  |  |  |
2022 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 620 |  |  |  | 1,333 |  |  |  | 1,963 |  |  |  |
2023 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 689 |  |  |  | 1,575 |  |  |  |
2024 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 678 |  |  |  |
|  | Losses and ALAE paid |  |  |  | 28,849 |  |  |  |
|  | Net unpaid losses and ALAE for 2015 – 2024 accident years |  |  |  | 23,908 |  |  |  |
|  | Net unpaid losses and ALAE for accident years before 2015 |  |  |  | 9,442 |  |  |  |
|  | Net unpaid losses and ALAE |  |  | $ | 33,350 |  |  |  |
* Unaudited required supplemental information

X
- Definition Tabular disclosure of the activity in the reserve for settling insured claims and expenses incurred in the claims settlement process for the period. The estimated liability includes the amount of money that will be required for future payments of (a) claims that have been reported to the insurer, (b) claims related to insured events that have occurred but that have not been reported to the insurer as of the date the liability is estimated, and (c) claim adjustment expenses. Claim adjustment expenses include costs incurred in the claim settlement process such as legal fees; outside adjuster fees; and costs to record, process, and adjust claims. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480081/944-40-50-3 + Details
Name: | us-gaap_ScheduleOfLiabilityForUnpaidClaimsAndClaimsAdjustmentExpense
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of undiscounted information about claims development by accident year for short-duration insurance contracts. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 9E -Publisher FASB -URI https://asc.fasb.org/1943274/2147480046/944-40-55-9E Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 4D -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480081/944-40-50-4D Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 4E -Publisher FASB -URI https://asc.fasb.org/1943274/2147480081/944-40-50-4E Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 4B -Publisher FASB -URI https://asc.fasb.org/1943274/2147480081/944-40-50-4B + Details
Name: | us-gaap_ShortdurationInsuranceContractsClaimsDevelopmentTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure for the reconciliation of claims development to the liability for unpaid claims and claim adjustment expense for short-duration insurance contracts. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 9E -Publisher FASB -URI https://asc.fasb.org/1943274/2147480046/944-40-55-9E Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 4C -Publisher FASB -URI https://asc.fasb.org/1943274/2147480081/944-40-50-4C + Details
Name: | us-gaap_ShortdurationInsuranceContractsReconciliationOfClaimsDevelopmentToLiabilityTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of average annual percentage payout of incurred claims by age, after reinsurance, for short-duration insurance contracts. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 4G -Publisher FASB -URI https://asc.fasb.org/1943274/2147480081/944-40-50-4G Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 9F -Publisher FASB -URI https://asc.fasb.org/1943274/2147480046/944-40-55-9F + Details
Name: | us-gaap_ShortdurationInsuranceContractsScheduleOfHistoricalClaimsDurationTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_SubsegmentsAxis=brka_GeicoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=brka_BerkshireHathawayInsuranceGroupMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=brka_PhysicalDamageInsuranceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=brka_AutoLiabilityInsuranceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsegmentsAxis=brka_BerkshireHathawayPrimaryGroupMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=brka_MedicalProfessionalLiabilityInsuranceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=brka_WorkersCompensationAndOtherCasualtyInsuranceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsegmentsAxis=brka_BerkshireHathawayReinsuranceGroupMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=us-gaap_PropertyInsuranceProductLineMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=brka_CasualtyInsuranceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |