Consolidated Statements of Earnings (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Revenues:
Investment gains/losses	$ 505		$ (106)
Total revenues	43,867		38,147
Costs and expenses:
Total costs and expenses	36,572		33,216
Earnings before income taxes	7,295		4,931
Income tax expense	2,278		1,565
Net earnings	5,017		3,366
Less: Earnings attributable to noncontrolling interests	125		121
Net earnings attributable to Berkshire Hathaway	4,892		3,245
Average common shares outstanding	1,643,181	[1]	1,650,944	[1]
Class A [Member]
Net earnings per share attributable to Berkshire Hathaway shareholders:
Net earnings per share attributable to Berkshire Hathaway shareholders	$ 2,977	[1]	$ 1,966	[1]
Insurance and Other [Member]
Revenues:
Insurance premiums earned	9,377		8,065
Sales and service revenues	22,418		19,264
Interest, dividend and other investment income	1,011		1,067
Investment gains/losses	434		(107)
Total revenues	33,240		28,289
Costs and expenses:
Insurance losses and loss adjustment expenses	5,144		4,771
Life, annuity and health insurance benefits	1,261		1,092
Insurance underwriting expenses	1,583		2,117
Cost of sales and services	18,284		15,596
Selling, general and administrative expenses	2,854		2,428
Interest expense	101		103
Total costs and expenses	29,227		26,107
Railroad, Utilities and Energy [Member]
Revenues:
Operating revenues	8,351		7,849
Other	49		47
Total revenues	8,400		7,896
Costs and expenses:
Cost of sales and operating expenses	6,111		5,870
Interest expense	447		428
Total costs and expenses	6,558		6,298
Finance and Financial Products [Member]
Revenues:
Interest, dividend and other investment income	341		375
Investment gains/losses	71		1
Derivative gains/losses	1,206		1,002
Other	609		584
Total revenues	2,227		1,962
Costs and expenses:
Interest expense	138		160
Other	649		651
Total costs and expenses	$ 787		$ 811

[1] Average shares outstanding include average Class A common shares and average Class B common shares determined on an equivalent Class A common stock basis. Net earnings per common share attributable to Berkshire Hathaway shown above represents net earnings per equivalent Class A common share. Net earnings per Class B common share is equal to one-fifteen-hundredth (1/1,500) of such amount.