Accumulated other comprehensive income - Reclassified Amounts (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013		Jun. 30, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Investment gains/losses	$ 492	$ 125	$ 997		$ 19
Reclassifications before income taxes	6,891	4,615	14,186		9,546
Applicable income taxes	2,279	1,384	4,557		2,949
Total amounts reclassified from other comprehensive income into net earnings	4,612	3,231	9,629		6,597
Insurance and Other [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Investment gains/losses	455	102	889		(5)
Finance and Financial Products [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Investment gains/losses	37	23	108		24
Portion Attributable to Berkshire Hathaway Shareholders [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other			61	[1]
Reclassifications before income taxes			(714)
Applicable income taxes			(243)
Total amounts reclassified from other comprehensive income into net earnings			(471)
Portion Attributable to Berkshire Hathaway Shareholders [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Insurance and Other [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Investment gains/losses			(707)
Portion Attributable to Berkshire Hathaway Shareholders [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Finance and Financial Products [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Investment gains/losses			(68)
Portion Attributable to Berkshire Hathaway Shareholders [Member] | Unrealized appreciation of investments, net [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications before income taxes			(775)
Applicable income taxes			(271)
Total amounts reclassified from other comprehensive income into net earnings			(504)
Portion Attributable to Berkshire Hathaway Shareholders [Member] | Unrealized appreciation of investments, net [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Insurance and Other [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Investment gains/losses			(707)
Portion Attributable to Berkshire Hathaway Shareholders [Member] | Unrealized appreciation of investments, net [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Finance and Financial Products [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Investment gains/losses			(68)
Portion Attributable to Berkshire Hathaway Shareholders [Member] | Foreign currency translation [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other			(29)	[1]
Reclassifications before income taxes			(29)
Total amounts reclassified from other comprehensive income into net earnings			(29)
Portion Attributable to Berkshire Hathaway Shareholders [Member] | Prior service and actuarial gains/losses of defined benefit pension plans [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other			83	[1]
Reclassifications before income taxes			83
Applicable income taxes			24
Total amounts reclassified from other comprehensive income into net earnings			59
Portion Attributable to Berkshire Hathaway Shareholders [Member] | Other AOCI transactions [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other			7	[1]
Reclassifications before income taxes			7
Applicable income taxes			4
Total amounts reclassified from other comprehensive income into net earnings			$ 3

[1] Amounts are included on various line items, and are immaterial individually and in the aggregate.