Consolidated Statements of Earnings (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Revenues:
Investment gains/losses	$ 917		$ 100		$ 1,273		$ 1,488
Other-than-temporary impairment losses on investments			(8)		(337)		(514)
Total revenues	41,050		33,739		117,743		105,733
Costs and expenses:
Total costs and expenses	35,114		30,376		102,261		94,871
Earnings before income taxes	5,936		3,363		15,482		10,862
Income tax expense	1,882		953		4,831		3,307
Net earnings	4,054		2,410		10,651		7,555
Less: Earnings attributable to noncontrolling interests	134		132		378		349
Net earnings attributable to Berkshire Hathaway shareholders	3,920		2,278		10,273		7,206
Average common shares outstanding	1,652,184	[1]	1,651,290	[1]	1,651,549	[1]	1,649,585	[1]
Class A [Member]
Net earnings per share attributable to Berkshire Hathaway shareholders:
Net earnings per share attributable to Berkshire Hathaway shareholders	$ 2,373	[1]	$ 1,380	[1]	$ 6,220	[1]	$ 4,368	[1]
Insurance and Other [Member]
Revenues:
Insurance premiums earned	8,851		7,645		25,344		24,076
Sales and service revenues	20,982		18,573		61,060		53,681
Interest, dividend and other investment income	994		1,051		3,481		3,754
Investment gains/losses	725		100		1,057		1,314
Other-than-temporary impairment losses on investments			(8)		(337)		(514)
Total revenues	31,552		27,361		90,605		82,311
Costs and expenses:
Insurance losses and loss adjustment expenses	5,016		3,827		14,373		16,107
Life, annuity and health insurance benefits	1,284		1,041		3,727		3,032
Insurance underwriting expenses	1,943		1,082		5,594		4,527
Cost of sales and services	16,992		15,281		49,409		44,095
Selling, general and administrative expenses	2,573		2,105		7,477		6,262
Interest expense	105		79		314		216
Total costs and expenses	27,913		23,415		80,894		74,239
Railroad, Utilities and Energy [Member]
Revenues:
Operating revenues	8,353		7,781		23,971		22,594
Other	66		47		154		115
Total revenues	8,419		7,828		24,125		22,709
Costs and expenses:
Cost of sales and operating expenses	5,930		5,675		17,567		16,898
Interest expense	439		428		1,306		1,280
Total costs and expenses	6,369		6,103		18,873		18,178
Finance and Financial Products [Member]
Revenues:
Interest, dividend and other investment income	366		384		1,113		1,141
Investment gains/losses	192				216		174
Derivative gains/losses	(118)		(2,443)		(184)		(2,356)
Other	639		609		1,868		1,754
Total revenues	1,079		(1,450)		3,013		713
Costs and expenses:
Interest expense	148		162		459		493
Other	684		696		2,035		1,961
Total costs and expenses	$ 832		$ 858		$ 2,494		$ 2,454

[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.