Condensed Financial Information - Statements of Earnings (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2010		Sep. 30, 2010		Jun. 30, 2010		Mar. 31, 2010		Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
From consolidated subsidiaries:
Total revenues	$ 37,955		$ 33,739		$ 38,274		$ 33,720		$ 36,165		$ 36,274		$ 31,709		$ 32,037		$ 143,688	$ 136,185	$ 112,493
Cost and expense items:
Income taxes																	4,568	5,607	3,538
Total costs and expenses																	128,374	117,134	100,941
Net earnings	3,048	[1]	2,278	[1]	3,417	[1]	1,511	[1]	4,377	[1]	2,989	[1]	1,968	[1]	3,633	[1]	10,254	12,967	8,055
Berkshire Hathaway (Parent) [Member]
From consolidated subsidiaries:
Dividends																	5,883	4,493	3,068
Undistributed earnings																	4,546	8,546	5,045
Total income from consolidated subsidiaries																	10,429	13,039	8,113
Other income																	101	115	8
Total revenues																	10,530	13,154	8,121
Cost and expense items:
General and administrative																	61	34	27
Interest to affiliates, net																	5	6	7
Other interest																	146	130	6
Income taxes																	64	17	26
Total costs and expenses																	276	187	66
Net earnings																	$ 10,254	$ 12,967	$ 8,055

[1] Includes realized investment gains/losses, other-than-temporary impairment losses on investments and derivative gains/losses. Derivative gains/losses include significant amounts related to non-cash changes in the fair value of long-term contracts arising from short-term changes in equity prices, interest rates and foreign currency rates, among other factors. After-tax investment and derivative gains/losses for the periods presented above are as follows (in millions): 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter Investment and derivative gains/losses - 2011 $ (82 ) $ 713 $ (1,534 ) $ 382 Investment and derivative gains/losses - 2010 1,411 (1,106 ) 202 1,367