Consolidated Statements of Earnings - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Sales and service revenues		$ 132,900	$ 125,700	$ 112,400
Investment gains/losses		1,410	7,553	9,373
Total revenues		242,137	223,604	210,943
Costs and expenses:
Interest expense		5,394	3,497	3,515
Total costs and expenses		221,237	190,860	175,875
Earnings before income taxes and equity in earnings of The Kraft Heinz Company		20,900	32,744	35,068
Equity in earnings (loss) of The Kraft Heinz Company		2,938	923	(122)
Earnings before income taxes		23,838	33,667	34,946
Income tax expense (benefit)		(21,515)	9,240	10,532
Net earnings		45,353	24,427	24,414
Earnings attributable to noncontrolling interests		413	353	331
Net earnings attributable to Berkshire Hathaway shareholders		$ 44,940	$ 24,074	$ 24,083
Equivalent Class A [Member]
Net earnings per share attributable to Berkshire Hathaway shareholders:
Net earnings per share attributable to Berkshire Hathaway shareholders		$ 27,326	$ 14,645	$ 14,656
Average equivalent shares outstanding		1,644,615	1,643,826	1,643,183
Equivalent Class B [Member]
Net earnings per share attributable to Berkshire Hathaway shareholders:
Net earnings per share attributable to Berkshire Hathaway shareholders	[1]	$ 18.22	$ 9.76	$ 9.77
Average equivalent shares outstanding		2,466,923,163	2,465,739,654	2,464,773,947
Insurance and Other [Member]
Revenues:
Insurance premiums earned		$ 60,597	$ 45,881	$ 41,294
Sales and service revenues		125,963	119,489	107,001
Interest, dividend and other investment income		5,144	4,725	5,357
Investment gains/losses		1,202	5,128	9,363
Total revenues		192,906	175,223	163,015
Costs and expenses:
Insurance losses and loss adjustment expenses		48,891	30,906	26,527
Life, annuity and health insurance benefits		5,618	5,131	5,413
Insurance underwriting expenses		9,321	7,713	7,517
Cost of sales and services		101,748	95,754	87,029
Selling, general and administrative expenses		16,241	16,478	13,723
Interest expense		1,740	445	460
Total costs and expenses		183,559	156,427	140,669
Railroad, Utilities and Energy [Member]
Revenues:
Total revenues		39,943	37,542	40,004
Costs and expenses:
Cost of sales and operating expenses		28,034	26,194	27,650
Interest expense		3,254	2,642	2,653
Total costs and expenses		31,288	28,836	30,303
Finance and Financial Products [Member]
Revenues:
Sales and service revenues		6,924	6,208	5,430
Interest, dividend and other investment income		1,438	1,455	1,510
Investment gains/losses		208	2,425	10
Derivative contract gains/losses		718	751	974
Total revenues		9,288	10,839	7,924
Costs and expenses:
Cost of sales and services		4,050	3,448	2,915
Selling, general and administrative expenses		1,940	1,739	1,586
Interest expense		400	410	402
Total costs and expenses		$ 6,390	$ 5,597	$ 4,903

[1] Net earnings per average equivalent Class B share outstanding are one-fifteen-hundredth of the equivalent Class A amount.