Accumulated other comprehensive income - Reclassified Amounts (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Investment gains/losses	$ 1,131	$ 505
Reclassifications before income taxes	6,598	7,295
Applicable income taxes	1,825	2,278
Total amounts reclassified from other comprehensive income into net earnings	4,773	5,017
Insurance and Other [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Investment gains/losses	1,059	434
Finance and Financial Products [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Investment gains/losses	72	71
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	(19)	49
Reclassifications before income taxes	(1,060)	(455)
Applicable income taxes	(375)	(163)
Total amounts reclassified from other comprehensive income into net earnings	(685)	(292)
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	(969)	(436)
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	(72)	(68)
Unrealized appreciation of investments, net [Member] | 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]
Reclassifications before income taxes	(1,041)	(504)
Applicable income taxes	(364)	(176)
Total amounts reclassified from other comprehensive income into net earnings	(677)	(328)
Unrealized appreciation of investments, net [Member] | 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	(969)	(436)
Unrealized appreciation of investments, net [Member] | 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	(72)	(68)
Prior service and actuarial gains/losses of defined benefit pension plans [Member] | 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	18	46
Reclassifications before income taxes	18	46
Applicable income taxes	4	12
Total amounts reclassified from other comprehensive income into net earnings	14	34
Other AOCI transactions [Member] | 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	(37)	3
Reclassifications before income taxes	(37)	3
Applicable income taxes	(15)	1
Total amounts reclassified from other comprehensive income into net earnings	$ (22)	$ 2