1.0.0.3 true Consolidated Statements of Cash Flows (USD $) In Millions false 1 $ false false Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 false 2 $ false false Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 false 3 $ false false Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 2 2 us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 3 2 us-gaap_ProfitLoss us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 true true 8441000000 8441 false false 2 true true 5596000000 5596 false false 3 true true 13567000000 13567 false false No definition available. No authoritative reference available. false 4 2 us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 5 2 us-gaap_GainLossOnInvestments us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 2837000000 2837 false false 2 false true 640000000 640 false false 3 false true -5598000000 -5598 false false No definition available. No authoritative reference available. false 6 2 us-gaap_Depreciation us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 3127000000 3127 false false 2 false true 2810000000 2810 false false 3 false true 2407000000 2407 false false No definition available. No authoritative reference available. false 7 2 us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesOther us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -149000000 -149 false false 2 false true -1248000000 -1248 false false 3 false true -268000000 -268 false false No definition available. No authoritative reference available. false 8 2 us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 9 2 us-gaap_IncreaseDecreaseInLossAndLossAdjustmentExpenseReserve us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 2165000000 2165 false false 2 false true 1466000000 1466 false false 3 false true -1164000000 -1164 false false No definition available. No authoritative reference available. false 10 2 brka_IncreaseDecreaseInDeferredChargesReinsuranceAssumed brka false debit duration monetary The change during the reporting period in deferred charges reinsurance assumed. false false false false false false false false false 1 false true -39000000 -39 false false 2 false true 64000000 64 false false 3 false true 196000000 196 false false The change during the reporting period in deferred charges reinsurance assumed. No authoritative reference available. false 11 2 us-gaap_IncreaseDecreaseInUnearnedPremiums us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -21000000 -21 false false 2 false true 1311000000 1311 false false 3 false true -713000000 -713 false false No definition available. No authoritative reference available. false 12 2 us-gaap_IncreaseDecreaseInReceivables us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 697000000 697 false false 2 false true -2222000000 -2222 false false 3 false true -977000000 -977 false false No definition available. No authoritative reference available. false 13 2 brka_IncreaseDecreaseInDerivativeContractAssetsAndLiabilities brka false credit duration monetary The change during the period in derivative contract assets and liabilities due to cash payments and receipts and changes in... false false false false false false false false false 1 false true -5441000000 -5441 false false 2 false true 7827000000 7827 false false 3 false true 2938000000 2938 false false The change during the period in derivative contract assets and liabilities due to cash payments and receipts and changes in the value of derivative instruments. No authoritative reference available. false 14 2 brka_IncreaseDecreaseInIncomeTaxes brka false debit duration monetary The change during the period due to cash payments and receipts from taxing authorities for taxes that are based on the... false false false false false false false false false 1 false true 2035000000 2035 false false 2 false true -2057000000 -2057 false false 3 false true 553000000 553 false false The change during the period due to cash payments and receipts from taxing authorities for taxes that are based on the reporting entity's earnings and the change during the reporting period for deferred and other tax assets and liabilities. No authoritative reference available. false 15 2 us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 2194000000 2194 false false 2 false true -2935000000 -2935 false false 3 false true 1609000000 1609 false false No definition available. No authoritative reference available. false 16 2 us-gaap_NetCashProvidedByUsedInOperatingActivities us-gaap true na duration monetary No definition available. false false false false false false false false false 1 false true 15846000000 15846 false false 2 false true 11252000000 11252 false false 3 false true 12550000000 12550 false false No definition available. No authoritative reference available. true 17 2 us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 18 2 brka_PaymentsToAcquireMarketableSecuritiesFixedMaturities brka false credit duration monetary The cash outflow from purchases of investments in securities having predetermined or determinable maturity dates. false false false false false false false false false 1 false true -10798000000 -10798 false false 2 false true -35615000000 -35615 false false 3 false true -13394000000 -13394 false false The cash outflow from purchases of investments in securities having predetermined or determinable maturity dates. No authoritative reference available. false 19 2 brka_PaymentsToAcquireMarketableSecuritiesEquitySecurities brka false credit duration monetary The cash outflow from purchases of investments in common stocks and other forms of securities that provide ownership... false false false false false false false false false 1 false true -4570000000 -4570 false false 2 false true -10140000000 -10140 false false 3 false true -19111000000 -19111 false false The cash outflow from purchases of investments in common stocks and other forms of securities that provide ownership interests in a corporation. No authoritative reference available. false 20 2 us-gaap_PaymentsToAcquireOtherInvestments us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -7068000000 -7068 false false 2 false true -14452000000 -14452 false false 3 false false 0 0 false false No definition available. No authoritative reference available. false 21 2 brka_ProceedsFromSaleOfMarketableSecuritiesFixedMaturities brka false debit duration monetary The cash inflow associated with the sale of investments in securities having predetermined or determinable maturity dates. false false false false false false false false false 1 false true 4338000000 4338 false false 2 false true 14796000000 14796 false false 3 false true 7821000000 7821 false false The cash inflow associated with the sale of investments in securities having predetermined or determinable maturity dates. No authoritative reference available. false 22 2 brka_ProceedsFromRedemptionsAndMaturitiesOfMarketableSecuritiesFixedMaturities brka false debit duration monetary The cash inflow associated with redemption or maturity of investments in securities having predetermined or determinable... false false false false false false false false false 1 false true 5234000000 5234 false false 2 false true 18550000000 18550 false false 3 false true 9158000000 9158 false false The cash inflow associated with redemption or maturity of investments in securities having predetermined or determinable maturity dates. No authoritative reference available. false 23 2 brka_ProceedsFromSaleOfMarketableSecuritiesEquitySecurities brka false debit duration monetary The cash inflow associated with the sale of investments in common stocks and other forms of securities that provide ownership... false false false false false false false false false 1 false true 5626000000 5626 false false 2 false true 6840000000 6840 false false 3 false true 8054000000 8054 false false The cash inflow associated with the sale of investments in common stocks and other forms of securities that provide ownership interests in a corporation. No authoritative reference available. false 24 2 us-gaap_PaymentsToAcquireLoansReceivable us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -854000000 -854 false false 2 false true -1446000000 -1446 false false 3 false true -1008000000 -1008 false false No definition available. No authoritative reference available. false 25 2 us-gaap_ProceedsFromCollectionOfLoansReceivable us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 796000000 796 false false 2 false true 740000000 740 false false 3 false true 1229000000 1229 false false No definition available. No authoritative reference available. false 26 2 us-gaap_PaymentsToAcquireBusinessesAndInterestInAffiliates us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -108000000 -108 false false 2 false true -6050000000 -6050 false false 3 false true -1602000000 -1602 false false No definition available. No authoritative reference available. false 27 2 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -4937000000 -4937 false false 2 false true -6138000000 -6138 false false 3 false true -5373000000 -5373 false false No definition available. No authoritative reference available. false 28 2 us-gaap_PaymentsForProceedsFromOtherInvestingActivities us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 1180000000 1180 false false 2 false true 849000000 849 false false 3 false true 798000000 798 false false No definition available. No authoritative reference available. false 29 2 us-gaap_NetCashProvidedByUsedInInvestingActivities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -11161000000 -11161 false false 2 false true -32066000000 -32066 false false 3 false true -13428000000 -13428 false false No definition available. No authoritative reference available. true 30 2 us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 33 2 us-gaap_ProceedsFromRepaymentsOfShortTermDebt us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -885000000 -885 false false 2 false true 1183000000 1183 false false 3 false true -596000000 -596 false false No definition available. No authoritative reference available. false 34 2 brka_PaymentsToMinorityShareholdersAndProceedsFromPaymentsForOtherFinancingActivities brka false credit duration monetary The cash outflow to return capital to noncontrolled interest, which generally occurs when noncontrolling shareholders reduce... false false false false false false false false false 1 false true -410000000 -410 false false 2 false true -132000000 -132 false false 3 false true 387000000 387 false false The cash outflow to return capital to noncontrolled interest, which generally occurs when noncontrolling shareholders reduce their ownership stake (in a subsidiary of the entity). Additionally, the balance includes the net cash inflow (outflow) from other financing activities. No authoritative reference available. false 35 2 us-gaap_NetCashProvidedByUsedInFinancingActivities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 233000000 233 false false 2 false true 2286000000 2286 false false 3 false true 1366000000 1366 false false No definition available. No authoritative reference available. true 36 2 us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 101000000 101 false false 2 false true -262000000 -262 false false 3 false true 98000000 98 false false No definition available. No authoritative reference available. false 37 2 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease us-gaap true na duration monetary No definition available. false false false false false false false false false 1 false true 5019000000 5019 false false 2 false true -18790000000 -18790 false false 3 false true 586000000 586 false false No definition available. No authoritative reference available. true 38 2 us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 39 2 us-gaap_CashAndCashEquivalentsAtCarryingValue us-gaap true debit instant monetary No definition available. false false false false false false true false false 1 false true 25539000000 25539 false false 2 false true 44329000000 44329 false false 3 false true 43743000000 43743 false false No definition available. No authoritative reference available. false 40 2 us-gaap_CashAndCashEquivalentsAtCarryingValue us-gaap true debit instant monetary No definition available. false false false false false false false true false 1 false true 30558000000 30558 false false 2 false true 25539000000 25539 false false 3 false true 44329000000 44329 false false No definition available. No authoritative reference available. false 41 0 na true na na na No definition available. false true false false false false false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. No authoritative reference available. false 70 2 us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 71 2 us-gaap_ProceedsFromOtherDebt us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 289000000 289 false false 2 false true 134000000 134 false false 3 false true 121000000 121 false false No definition available. No authoritative reference available. false 72 2 us-gaap_RepaymentsOfOtherDebt us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -739000000 -739 false false 2 false true -233000000 -233 false false 3 false true -995000000 -995 false false No definition available. No authoritative reference available. false 78 2 us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 79 2 us-gaap_CashAndCashEquivalentsAtCarryingValue us-gaap true debit instant monetary No definition available. false false false false false false true false false 1 false true 24302000000 24302 false false 2 false true 37703000000 37703 false false 3 false false 0 0 false false No definition available. No authoritative reference available. false 80 2 us-gaap_CashAndCashEquivalentsAtCarryingValue us-gaap true debit instant monetary No definition available. false false false false false false false true false 1 false true 27917000000 27917 false false 2 false true 24302000000 24302 false false 3 false true 37703000000 37703 false false No definition available. No authoritative reference available. false 81 0 na true na na na No definition available. false true false false false false false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. No authoritative reference available. false 110 2 us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 111 2 us-gaap_ProceedsFromOtherDebt us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 1241000000 1241 false false 2 false true 2147000000 2147 false false 3 false true 3538000000 3538 false false No definition available. No authoritative reference available. false 112 2 us-gaap_RepaymentsOfOtherDebt us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -444000000 -444 false false 2 false true -2147000000 -2147 false false 3 false true -1149000000 -1149 false false No definition available. No authoritative reference available. false 118 2 us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 119 2 us-gaap_CashAndCashEquivalentsAtCarryingValue us-gaap true debit instant monetary No definition available. false false false false false false true false false 1 false true 280000000 280 false false 2 false true 1178000000 1178 false false 3 false false 0 0 false false No definition available. No authoritative reference available. false 120 2 us-gaap_CashAndCashEquivalentsAtCarryingValue us-gaap true debit instant monetary No definition available. false false false false false false false true false 1 false true 429000000 429 false false 2 false true 280000000 280 false false 3 false true 1178000000 1178 false false No definition available. No authoritative reference available. false 121 0 na true na na na No definition available. false true false false false false false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. No authoritative reference available. false 150 2 us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 151 2 us-gaap_ProceedsFromOtherDebt us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 1584000000 1584 false false 2 false true 5195000000 5195 false false 3 false true 1153000000 1153 false false No definition available. No authoritative reference available. false 152 2 us-gaap_RepaymentsOfOtherDebt us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -403000000 -403 false false 2 false true -3861000000 -3861 false false 3 false true -1093000000 -1093 false false No definition available. No authoritative reference available. false 158 2 us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 159 2 us-gaap_CashAndCashEquivalentsAtCarryingValue us-gaap true debit instant monetary No definition available. false false false false false false true false false 1 false true 957000000 957 false false 2 false true 5448000000 5448 false false 3 false false 0 0 false false No definition available. No authoritative reference available. false 160 2 us-gaap_CashAndCashEquivalentsAtCarryingValue us-gaap true debit instant monetary No definition available. false false false false false false false true false 1 true true 2212000000 2212 false false 2 true true 957000000 957 false false 3 true true 5448000000 5448 false false No definition available. No authoritative reference available. false false 3 58 false Millions UnKnown UnKnown false true