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Pension plans - Defined contribution pension plans - Narrative (Detail) - USD ($) $ in Billions | 12 Months Ended
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Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Defined Contribution Plan [Abstract] |  |  |
Contributions to defined contribution plans | $ 1.3 | $ 1.1 | $ 0.8

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- Definition Amount of employer contributions to a defined contribution plan. + References No definition available. + Details
Name: | brka_DefinedContributionPlanEmployerContributionAmount
Namespace Prefix: | brka_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanInformationAboutPlanAssetsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration