3.25.3 html 702 424 1 true 173 0 false 17 false false R1.htm 75000 - Document - Document and Entity Information Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DocumentDocumentAndEntityInformation Document and Entity Information Cover 1 false false R2.htm 75010 - Statement - Consolidated Balance Sheets Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_StatementConsolidatedBalanceSheets Consolidated Balance Sheets Statements 2 false false R3.htm 75020 - Statement - Consolidated Balance Sheets (Parenthetical) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_StatementConsolidatedBalanceSheetsParenthetical Consolidated Balance Sheets (Parenthetical) Statements 3 false false R4.htm 75030 - Statement - Consolidated Statements of Earnings Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_StatementConsolidatedStatementsOfEarnings Consolidated Statements of Earnings Statements 4 false false R5.htm 75040 - Statement - Consolidated Statements of Earnings (Parenthetical) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_StatementConsolidatedStatementsOfEarningsParenthetical Consolidated Statements of Earnings (Parenthetical) Statements 5 false false R6.htm 75050 - Statement - Consolidated Statements of Comprehensive Income Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/StatementConsolidatedStatementsOfComprehensiveIncome1 Consolidated Statements of Comprehensive Income Statements 6 false false R7.htm 75060 - Statement - Consolidated Statements of Changes in Shareholders' Equity Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_StatementConsolidatedStatementsOfChangesInShareholdersEquity Consolidated Statements of Changes in Shareholders' Equity Statements 7 false false R8.htm 75070 - Statement - Consolidated Statements of Cash Flows Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_StatementConsolidatedStatementsOfCashFlows Consolidated Statements of Cash Flows Statements 8 false false R9.htm 995410 - Disclosure - Pay vs Performance Disclosure Sheet http://xbrl.sec.gov/ecd/role/PvpDisclosure Pay vs Performance Disclosure Notes 9 false false R10.htm 995445 - Disclosure - Insider Trading Arrangements Sheet http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements Insider Trading Arrangements Notes 10 false false R11.htm 995455 - Disclosure - General Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureGeneral General Notes 11 false false R12.htm 995465 - Disclosure - New accounting and financial reporting pronouncements Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureNewAccountingAndFinancialReportingPronouncements1 New accounting and financial reporting pronouncements Notes 12 false false R13.htm 995475 - Disclosure - Investments in fixed maturity securities Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureInvestmentsInFixedMaturitySecurities Investments in fixed maturity securities Notes 13 false false R14.htm 995485 - Disclosure - Investments in equity securities Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureInvestmentsInEquitySecurities Investments in equity securities Notes 14 false false R15.htm 995495 - Disclosure - Equity method investments Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureEquityMethodInvestments Equity method investments Notes 15 false false R16.htm 995505 - Disclosure - Investment gains (losses) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureInvestmentGainsLosses Investment gains (losses) Notes 16 false false R17.htm 995515 - Disclosure - Loans and finance receivables Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureLoansAndFinanceReceivables Loans and finance receivables Notes 17 false false R18.htm 995525 - Disclosure - Other receivables Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureOtherReceivables Other receivables Notes 18 false false R19.htm 995535 - Disclosure - Inventories Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureInventories Inventories Notes 19 false false R20.htm 995545 - Disclosure - Property, plant and equipment including equipment held for lease Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosurePropertyPlantAndEquipmentIncludingEquipmentHeldForLease Property, plant and equipment including equipment held for lease Notes 20 false false R21.htm 995555 - Disclosure - Goodwill and other intangible assets Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureGoodwillAndOtherIntangibleAssets Goodwill and other intangible assets Notes 21 false false R22.htm 995565 - Disclosure - Unpaid losses and loss adjustment expenses Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureUnpaidLossesAndLossAdjustmentExpenses Unpaid losses and loss adjustment expenses Notes 22 false false R23.htm 995575 - Disclosure - Retroactive reinsurance contracts Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureRetroactiveReinsuranceContracts Retroactive reinsurance contracts Notes 23 false false R24.htm 995585 - Disclosure - Long-duration insurance contracts Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureLongdurationInsuranceContracts Long-duration insurance contracts Notes 24 false false R25.htm 995595 - Disclosure - Notes payable and other borrowings Notes http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureNotesPayableAndOtherBorrowings Notes payable and other borrowings Notes 25 false false R26.htm 995605 - Disclosure - Fair value measurements Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureFairValueMeasurements Fair value measurements Notes 26 false false R27.htm 995615 - Disclosure - Common stock Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureCommonStock Common stock Notes 27 false false R28.htm 995625 - Disclosure - Income taxes Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureIncomeTaxes Income taxes Notes 28 false false R29.htm 995635 - Disclosure - Accumulated other comprehensive income Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureAccumulatedOtherComprehensiveIncome Accumulated other comprehensive income Notes 29 false false R30.htm 995645 - Disclosure - Supplemental cash flow information Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureSupplementalCashFlowInformation Supplemental cash flow information Notes 30 false false R31.htm 995655 - Disclosure - Contingencies and commitments Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureContingenciesAndCommitments1 Contingencies and commitments Notes 31 false false R32.htm 995665 - Disclosure - Revenues from contracts with customers Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureRevenuesFromContractsWithCustomers Revenues from contracts with customers Notes 32 false false R33.htm 995675 - Disclosure - Business segment data Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureBusinessSegmentData Business segment data Notes 33 false false R34.htm 995685 - Disclosure - New accounting and financial reporting pronouncements (Policies) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureNewAccountingAndFinancialReportingPronouncementsPolicies New accounting and financial reporting pronouncements (Policies) Policies 34 false false R35.htm 995695 - Disclosure - General (Tables) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureGeneralTables General (Tables) Tables http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureGeneral 35 false false R36.htm 995715 - Disclosure - Investments in fixed maturity securities (Tables) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureInvestmentsInFixedMaturitySecuritiesTables Investments in fixed maturity securities (Tables) Tables http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureInvestmentsInFixedMaturitySecurities 36 false false R37.htm 995725 - Disclosure - Investments in equity securities (Tables) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureInvestmentsInEquitySecuritiesTables Investments in equity securities (Tables) Tables http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureInvestmentsInEquitySecurities 37 false false R38.htm 995735 - Disclosure - Equity method investments (Tables) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureEquityMethodInvestmentsTables Equity method investments (Tables) Tables http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureEquityMethodInvestments 38 false false R39.htm 995745 - Disclosure - Investment gains (losses) (Tables) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureInvestmentGainsLossesTables Investment gains (losses) (Tables) Tables http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureInvestmentGainsLosses 39 false false R40.htm 995755 - Disclosure - Loans and finance receivables (Tables) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureLoansAndFinanceReceivablesTables Loans and finance receivables (Tables) Tables http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureLoansAndFinanceReceivables 40 false false R41.htm 995765 - Disclosure - Other receivables (Tables) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureOtherReceivablesTables Other receivables (Tables) Tables http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureOtherReceivables 41 false false R42.htm 995775 - Disclosure - Inventories (Tables) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureInventoriesTables Inventories (Tables) Tables http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureInventories 42 false false R43.htm 995785 - Disclosure - Property, plant and equipment including equipment held for lease (Tables) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosurePropertyPlantAndEquipmentIncludingEquipmentHeldForLeaseTables Property, plant and equipment including equipment held for lease (Tables) Tables http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosurePropertyPlantAndEquipmentIncludingEquipmentHeldForLease 43 false false R44.htm 995795 - Disclosure - Equipment held for lease (Tables) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureEquipmentHeldForLeaseTables Equipment held for lease (Tables) Tables 44 false false R45.htm 995805 - Disclosure - Goodwill and other intangible assets (Tables) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureGoodwillAndOtherIntangibleAssetsTables Goodwill and other intangible assets (Tables) Tables http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureGoodwillAndOtherIntangibleAssets 45 false false R46.htm 995815 - Disclosure - Unpaid losses and loss adjustment expenses (Tables) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureUnpaidLossesAndLossAdjustmentExpensesTables Unpaid losses and loss adjustment expenses (Tables) Tables http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureUnpaidLossesAndLossAdjustmentExpenses 46 false false R47.htm 995825 - Disclosure - Retroactive reinsurance contracts (Tables) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureRetroactiveReinsuranceContractsTables Retroactive reinsurance contracts (Tables) Tables http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureRetroactiveReinsuranceContracts 47 false false R48.htm 995835 - Disclosure - Long-duration insurance contracts (Tables) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureLongdurationInsuranceContractsTables Long-duration insurance contracts (Tables) Tables http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureLongdurationInsuranceContracts 48 false false R49.htm 995845 - Disclosure - Notes payable and other borrowings (Tables) Notes http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureNotesPayableAndOtherBorrowingsTables Notes payable and other borrowings (Tables) Tables http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureNotesPayableAndOtherBorrowings 49 false false R50.htm 995855 - Disclosure - Fair value measurements (Tables) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureFairValueMeasurementsTables Fair value measurements (Tables) Tables http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureFairValueMeasurements 50 false false R51.htm 995865 - Disclosure - Common stock (Tables) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureCommonStockTables Common stock (Tables) Tables http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureCommonStock 51 false false R52.htm 995875 - Disclosure - Accumulated other comprehensive income (Tables) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureAccumulatedOtherComprehensiveIncomeTables Accumulated other comprehensive income (Tables) Tables http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureAccumulatedOtherComprehensiveIncome 52 false false R53.htm 995885 - Disclosure - Supplemental cash flow information (Tables) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureSupplementalCashFlowInformationTables Supplemental cash flow information (Tables) Tables http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureSupplementalCashFlowInformation 53 false false R54.htm 995895 - Disclosure - Revenues from contracts with customers (Tables) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureRevenuesFromContractsWithCustomersTables Revenues from contracts with customers (Tables) Tables http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureRevenuesFromContractsWithCustomers 54 false false R55.htm 995905 - Disclosure - Business segment data (Tables) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureBusinessSegmentDataTables Business segment data (Tables) Tables http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureBusinessSegmentData 55 false false R56.htm 995915 - Disclosure - General - Summary of Reclassifications to Amounts Previously Reported (Details) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureGeneralSummaryOfReclassificationsToAmountsPreviouslyReportedDetails General - Summary of Reclassifications to Amounts Previously Reported (Details) Details 56 false false R57.htm 995925 - Disclosure - Investments in fixed maturity securities (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureInvestmentsInFixedMaturitySecuritiesDetail Investments in fixed maturity securities (Detail) Details http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureInvestmentsInFixedMaturitySecuritiesTables 57 false false R58.htm 995935 - Disclosure - Investments in fixed maturity securities - Narrative (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureInvestmentsInFixedMaturitySecuritiesNarrativeDetail Investments in fixed maturity securities - Narrative (Detail) Details 58 false false R59.htm 995945 - Disclosure - Investments in fixed maturity securities - Amortized cost and estimated fair value of securities with fixed maturities (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureInvestmentsInFixedMaturitySecuritiesAmortizedCostAndEstimatedFairValueOfSecuritiesWithFixedMaturitiesDetail Investments in fixed maturity securities - Amortized cost and estimated fair value of securities with fixed maturities (Detail) Details 59 false false R60.htm 995955 - Disclosure - Investments in equity securities (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureInvestmentsInEquitySecuritiesDetail Investments in equity securities (Detail) Details http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureInvestmentsInEquitySecuritiesTables 60 false false R61.htm 995965 - Disclosure - Investments in equity securities - Narrative (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureInvestmentsInEquitySecuritiesNarrativeDetail Investments in equity securities - Narrative (Detail) Details 61 false false R62.htm 995975 - Disclosure - Equity method investments - Narrative (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureEquityMethodInvestmentsNarrativeDetail Equity method investments - Narrative (Detail) Details 62 false false R63.htm 995985 - Disclosure - Equity method investments - Summary of carrying value and fair value of investments (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureEquityMethodInvestmentsSummaryOfCarryingValueAndFairValueOfInvestmentsDetail Equity method investments - Summary of carrying value and fair value of investments (Detail) Details 63 false false R64.htm 995995 - Disclosure - Equity method investments - Summary of earnings and distributions received from equity method investments (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureEquityMethodInvestmentsSummaryOfEarningsAndDistributionsReceivedFromEquityMethodInvestmentsDetail Equity method investments - Summary of earnings and distributions received from equity method investments (Detail) Details 64 false false R65.htm 996005 - Disclosure - Equity method investments - Unaudited financial information (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureEquityMethodInvestmentsUnauditedFinancialInformationDetail Equity method investments - Unaudited financial information (Detail) Details 65 false false R66.htm 996015 - Disclosure - Investment gains (losses) (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureInvestmentGainsLossesDetail Investment gains (losses) (Detail) Details http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureInvestmentGainsLossesTables 66 false false R67.htm 996025 - Disclosure - Investment gains (losses) - Narrative (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureInvestmentGainsLossesNarrativeDetail Investment gains (losses) - Narrative (Detail) Details http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureInvestmentGainsLossesTables 67 false false R68.htm 996035 - Disclosure - Loans and finance receivables (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureLoansAndFinanceReceivablesDetail Loans and finance receivables (Detail) Details http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureLoansAndFinanceReceivablesTables 68 false false R69.htm 996045 - Disclosure - Loans and finance receivables - Schedule of reconciliation of allowance for credit losses on loans and finance receivables (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureLoansAndFinanceReceivablesScheduleOfReconciliationOfAllowanceForCreditLossesOnLoansAndFinanceReceivablesDetail Loans and finance receivables - Schedule of reconciliation of allowance for credit losses on loans and finance receivables (Detail) Details 69 false false R70.htm 996055 - Disclosure - Loans and finance receivables - Narrative (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureLoansAndFinanceReceivablesNarrativeDetail Loans and finance receivables - Narrative (Detail) Details 70 false false R71.htm 996065 - Disclosure - Loans and finance receivables - Summary of performing and non-performing home loans before discounts and allowances by year of loan origination (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureLoansAndFinanceReceivablesSummaryOfPerformingAndNonPerformingHomeLoansBeforeDiscountsAndAllowancesByYearOfLoanOriginationDetail Loans and finance receivables - Summary of performing and non-performing home loans before discounts and allowances by year of loan origination (Detail) Details 71 false false R72.htm 996075 - Disclosure - Other receivables (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureOtherReceivablesDetail Other receivables (Detail) Details http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureOtherReceivablesTables 72 false false R73.htm 996085 - Disclosure - Other receivables - Narrative (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureOtherReceivablesNarrativeDetail Other receivables - Narrative (Detail) Details 73 false false R74.htm 996095 - Disclosure - Inventories (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureInventoriesDetail Inventories (Detail) Details http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureInventoriesTables 74 false false R75.htm 996105 - Disclosure - Inventories - Narrative (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureInventoriesNarrativeDetail Inventories - Narrative (Detail) Details 75 false false R76.htm 996115 - Disclosure - Property, plant and equipment (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosurePropertyPlantAndEquipmentDetail Property, plant and equipment (Detail) Details http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosurePropertyPlantAndEquipmentIncludingEquipmentHeldForLeaseTables 76 false false R77.htm 996125 - Disclosure - Property, plant and equipment - Depreciation expense (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosurePropertyPlantAndEquipmentDepreciationExpenseDetail Property, plant and equipment - Depreciation expense (Detail) Details 77 false false R78.htm 996135 - Disclosure - Equipment held for lease (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureEquipmentHeldForLeaseDetail Equipment held for lease (Detail) Details http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureEquipmentHeldForLeaseTables 78 false false R79.htm 996145 - Disclosure - Equipment held for lease - Narrative (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureEquipmentHeldForLeaseNarrativeDetail Equipment held for lease - Narrative (Detail) Details 79 false false R80.htm 996155 - Disclosure - Equipment held for lease - Summary of fixed and variable operating lease revenues (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureEquipmentHeldForLeaseSummaryOfFixedAndVariableOperatingLeaseRevenuesDetail Equipment held for lease - Summary of fixed and variable operating lease revenues (Detail) Details 80 false false R81.htm 996165 - Disclosure - Goodwill and other intangible assets - Goodwill (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureGoodwillAndOtherIntangibleAssetsGoodwillDetail Goodwill and other intangible assets - Goodwill (Detail) Details 81 false false R82.htm 996175 - Disclosure - Goodwill and other intangible assets - Goodwill (Parenthetical) (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureGoodwillAndOtherIntangibleAssetsGoodwillParentheticalDetail Goodwill and other intangible assets - Goodwill (Parenthetical) (Detail) Details 82 false false R83.htm 996185 - Disclosure - Goodwill and other intangible assets - Intangible assets (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureGoodwillAndOtherIntangibleAssetsIntangibleAssetsDetail Goodwill and other intangible assets - Intangible assets (Detail) Details 83 false false R84.htm 996195 - Disclosure - Goodwill and other intangible assets - Intangible assets - Narrative (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureGoodwillAndOtherIntangibleAssetsIntangibleAssetsNarrativeDetail Goodwill and other intangible assets - Intangible assets - Narrative (Detail) Details 84 false false R85.htm 996205 - Disclosure - Unpaid losses and loss adjustment expenses - Reconciliation of changes in claim liabilities (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureUnpaidLossesAndLossAdjustmentExpensesReconciliationOfChangesInClaimLiabilitiesDetail Unpaid losses and loss adjustment expenses - Reconciliation of changes in claim liabilities (Detail) Details 85 false false R86.htm 996215 - Disclosure - Unpaid losses and loss adjustment expenses - Narrative (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureUnpaidLossesAndLossAdjustmentExpensesNarrativeDetail Unpaid losses and loss adjustment expenses - Narrative (Detail) Details 86 false false R87.htm 996225 - Disclosure - Retroactive reinsurance contracts - Reconciliation of changes in claim liabilities and incurred losses and loss adjustment expenses (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureRetroactiveReinsuranceContractsReconciliationOfChangesInClaimLiabilitiesAndIncurredLossesAndLossAdjustmentExpensesDetail Retroactive reinsurance contracts - Reconciliation of changes in claim liabilities and incurred losses and loss adjustment expenses (Detail) Details 87 false false R88.htm 996235 - Disclosure - Retroactive reinsurance contracts - Narrative (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureRetroactiveReinsuranceContractsNarrativeDetail Retroactive reinsurance contracts - Narrative (Detail) Details 88 false false R89.htm 996245 - Disclosure - Long-duration insurance contracts - Summary of life, annuity and health insurance benefits liabilities (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureLongdurationInsuranceContractsSummaryOfLifeAnnuityAndHealthInsuranceBenefitsLiabilitiesDetail Long-duration insurance contracts - Summary of life, annuity and health insurance benefits liabilities (Detail) Details 89 false false R90.htm 996255 - Disclosure - Long-duration insurance contracts - Summary of changes in discounted present values of expected future policy benefits and expected future net premiums (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureLongdurationInsuranceContractsSummaryOfChangesInDiscountedPresentValuesOfExpectedFuturePolicyBenefitsAndExpectedFutureNetPremium Long-duration insurance contracts - Summary of changes in discounted present values of expected future policy benefits and expected future net premiums (Detail) Details 90 false false R91.htm 996265 - Disclosure - Long-duration insurance contracts - Summary of Other Information Relating to Long-Duration Insurance Liabilities (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureLongdurationInsuranceContractsSummaryOfOtherInformationRelatingToLongdurationInsuranceLiabilitiesDetail Long-duration insurance contracts - Summary of Other Information Relating to Long-Duration Insurance Liabilities (Detail) Details 91 false false R92.htm 996275 - Disclosure - Long-duration insurance contracts - Summary of gross premiums earned and net interest expense (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureLongdurationInsuranceContractsSummaryOfGrossPremiumsEarnedAndNetInterestExpenseDetail Long-duration insurance contracts - Summary of gross premiums earned and net interest expense (Detail) Details 92 false false R93.htm 996305 - Disclosure - Notes payable and other borrowings (Detail) Notes http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureNotesPayableAndOtherBorrowingsDetail Notes payable and other borrowings (Detail) Details http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureNotesPayableAndOtherBorrowingsTables 93 false false R94.htm 996315 - Disclosure - Notes payable and other borrowings - Narrative (Detail) Notes http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureNotesPayableAndOtherBorrowingsNarrativeDetail Notes payable and other borrowings - Narrative (Detail) Details 94 false false R95.htm 996325 - Disclosure - Fair value measurements - Financial assets and liabilities (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureFairValueMeasurementsFinancialAssetsAndLiabilitiesDetail Fair value measurements - Financial assets and liabilities (Detail) Details 95 false false R96.htm 996335 - Disclosure - Fair value measurements - Significant unobservable inputs (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureFairValueMeasurementsSignificantUnobservableInputsDetail Fair value measurements - Significant unobservable inputs (Detail) Details 96 false false R97.htm 996345 - Disclosure - Fair value measurements - Other information (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureFairValueMeasurementsOtherInformationDetail Fair value measurements - Other information (Detail) Details 97 false false R98.htm 996355 - Disclosure - Common stock - Narrative (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureCommonStockNarrativeDetail Common stock - Narrative (Detail) Details 98 false false R99.htm 996365 - Disclosure - Common stock (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureCommonStockDetail Common stock (Detail) Details http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureCommonStockTables 99 false false R100.htm 996375 - Disclosure - Common stock (Parenthetical) (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureCommonStockParentheticalDetail Common stock (Parenthetical) (Detail) Details http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureCommonStockTables 100 false false R101.htm 996385 - Disclosure - Income taxes - Narrative (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureIncomeTaxesNarrativeDetail Income taxes - Narrative (Detail) Details 101 false false R102.htm 996395 - Disclosure - Accumulated other comprehensive income (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureAccumulatedOtherComprehensiveIncomeDetail Accumulated other comprehensive income (Detail) Details http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureAccumulatedOtherComprehensiveIncomeTables 102 false false R103.htm 996405 - Disclosure - Supplemental cash flow information (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureSupplementalCashFlowInformationDetail Supplemental cash flow information (Detail) Details http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureSupplementalCashFlowInformationTables 103 false false R104.htm 996415 - Disclosure - Contingencies and commitments - Narrative (Details) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureContingenciesAndCommitmentsNarrativeDetails Contingencies and commitments - Narrative (Details) Details 104 false false R105.htm 996425 - Disclosure - Revenue from contracts with customers disaggregated by reportable segment and source of revenue (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/Role_DisclosureRevenueFromContractsWithCustomersDisaggregatedByReportableSegmentAndSourceOfRevenueDetail Revenue from contracts with customers disaggregated by reportable segment and source of revenue (Detail) Details 105 false false R106.htm 996435 - Disclosure - Revenue from contracts with customers transaction prices allocated to significant unsatisfied remaining performance obligations and timing of when performance obligations expected to be satisfied (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureRevenueFromContractsWithCustomersTransactionPricesAllocatedToSignificantUnsatisfiedRemainingPerformanceObligationsAndTimingOfWhenP Revenue from contracts with customers transaction prices allocated to significant unsatisfied remaining performance obligations and timing of when performance obligations expected to be satisfied (Detail) Details 106 false false R107.htm 996445 - Disclosure - Revenue from contracts with customers transaction prices allocated to significant unsatisfied remaining performance obligations and timing of when performance obligations expected to be satisfied (Detail 1) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureRevenueFromContractsWithCustomersTransactionPricesAllocatedToSignificantUnsatisfiedRemainingPerformanceObligationsAndTimingOfWhenP1 Revenue from contracts with customers transaction prices allocated to significant unsatisfied remaining performance obligations and timing of when performance obligations expected to be satisfied (Detail 1) Details 107 false false R108.htm 996455 - Disclosure - Business segment data - Narrative (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureBusinessSegmentDataNarrativeDetail Business segment data - Narrative (Detail) Details 108 false false R109.htm 996465 - Disclosure - Business segment data - Earnings data (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureBusinessSegmentDataEarningsDataDetail Business segment data - Earnings data (Detail) Details 109 false false R110.htm 996475 - Disclosure - Business segment data - Reconciliations of Revenues and Earnings before income taxes (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureBusinessSegmentDataReconciliationsOfRevenuesAndEarningsBeforeIncomeTaxesDetail Business segment data - Reconciliations of Revenues and Earnings before income taxes (Detail) Details 110 false false R111.htm 996485 - Disclosure - Business segment data - Additional tabular disclosures (Detail) Sheet http://www.berkshirehathaway.com/20250930/taxonomy/role/DisclosureBusinessSegmentDataAdditionalTabularDisclosuresDetail Business segment data - Additional tabular disclosures (Detail) Details 111 false false All Reports Book All Reports brka-20250930.htm brka-20250930.xsd http://fasb.org/us-gaap/2025 http://xbrl.sec.gov/dei/2025 http://xbrl.sec.gov/ecd/2025 false false