Condensed Financial Information - Statements of Cash Flows (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended																12 Months Ended
	Aug. 31, 2016	Dec. 31, 2016		Sep. 30, 2016	[1]	Jun. 30, 2016	[1]	Mar. 31, 2016		Dec. 31, 2015		Sep. 30, 2015	[1]	Jun. 30, 2015	[1]	Mar. 31, 2015		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net earnings attributable to Berkshire Hathaway shareholders		$ 6,286	[1]	$ 7,198		$ 5,001		$ 5,589	[1]	$ 5,478	[1]	$ 9,428		$ 4,013		$ 5,164	[1]	$ 24,074	$ 24,083	$ 19,872
Adjustments to reconcile net earnings to cash flows from operating activities:
Investment gains/losses																		(7,553)	(9,373)	(3,575)
Income taxes payable																		4,044	5,718	4,905
Other																		(161)	751	(341)
Net cash flows from operating activities																		32,535	31,491	32,010
Cash flows from investing activities:
Purchases of U.S. Treasury Bills and fixed maturity securities																		(96,568)	(17,891)	(12,562)
Net cash flows from investing activities																		(84,267)	(28,001)	(20,326)
Cash flows from financing activities:
Net cash flows from financing activities																		12,791	3,803	2,731
Increase (decrease) in cash and cash equivalents																		(39,113)	7,128	14,126
Cash and cash equivalents at beginning of year								67,161								60,033		67,161	60,033	45,907
Cash and cash equivalents at end of year		28,048								67,161								28,048	67,161	60,033
Other cash flow information:
Income taxes paid																		4,719	4,535	4,014
Berkshire Hathaway Inc. (Parent) [Member]
Cash flows from operating activities:
Net earnings attributable to Berkshire Hathaway shareholders																		24,074	24,083	19,872
Adjustments to reconcile net earnings to cash flows from operating activities:
Investment gains/losses																		(700)	(6,854)
Undistributed earnings of subsidiaries																		(13,264)	(8,508)	(14,496)
Non-cash dividends from subsidiaries																			(3,938)
Income taxes payable																		629	2,227	136
Other																		(161)	222	(75)
Net cash flows from operating activities																		10,578	7,232	5,437
Cash flows from investing activities:
Redemption (purchase) of Kraft Heinz investments																		8,320	(5,258)
Investments in and advances to/repayments from subsidiaries																		(26,398)	(2,274)	1,673
Net cash flows from investing activities																		(26,283)	(7,532)	1,673
Cash flows from financing activities:
Proceeds from borrowings																		9,278	3,165	832
Repayments of borrowings	$ (750)																	(1,125)	(1,775)	(792)
Acquisitions of noncontrolling interests																		(2)	(10)	(1,231)
Other																		166	80	118
Net cash flows from financing activities																		8,317	1,460	(1,073)
Increase (decrease) in cash and cash equivalents																		(7,388)	1,160	6,037
Cash and cash equivalents at beginning of year								$ 10,609								$ 9,449		10,609	9,449	3,412
Cash and cash equivalents at end of year		$ 3,221								$ 10,609								3,221	10,609	9,449
Other cash flow information:
Income taxes paid																		3,583	3,180	2,512
Interest paid																		307	206	$ 233
Non-cash investments in subsidiaries																			$ 3,938
Berkshire Hathaway Inc. (Parent) [Member] | U.S. Treasury Bills [Member]
Cash flows from investing activities:
Purchases of U.S. Treasury Bills and fixed maturity securities																		(9,350)
Sales and maturities of U.S. Treasury Bills																		$ 1,145

[1] Includes investment and derivative gains/losses. 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-2016 $ 1,852 $ 394 $ 2,347 $ 1,904 Investment and derivative gains/losses-2015 920 123 4,877 805