Consolidated Statements of Earnings - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Sales and service revenues		$ 45,427		$ 131,191
Total revenues		63,450	$ 59,507	184,123	$ 181,133
Investment and derivative contract gains/losses:
Investments gains (losses)		14,569	657	12,750	1,262
Derivative contract gains (losses)		137	308	303	703
Investment and derivative gains/losses		14,706	965	13,053	1,965
Costs and expenses:
Total costs and expenses		55,325	55,147	161,498	166,583
Earnings before income taxes and equity method earnings		22,831	5,325	35,678	16,515
Equity method earnings		316	305	1,044	932
Earnings before income taxes		23,147	5,630	36,722	17,447
Income tax expense		4,440	1,427	7,009	4,750
Net earnings		18,707	4,203	29,713	12,697
Earnings attributable to noncontrolling interests		167	136	300	308
Net earnings attributable to Berkshire Hathaway shareholders		$ 18,540	$ 4,067	$ 29,413	$ 12,389
Equivalent Class A [Member]
Net earnings (loss) per share attributable to Berkshire Hathaway shareholders:
Net earnings per average equivalent share	[1]	$ 11,280	$ 2,473	$ 17,885	$ 7,533
Equivalent Class B [Member]
Net earnings (loss) per share attributable to Berkshire Hathaway shareholders:
Net earnings per average equivalent share	[1]	$ 7.52	$ 1.65	$ 11.92	$ 5.02
Class A [Member]
Net earnings (loss) per share attributable to Berkshire Hathaway shareholders:
Average shares outstanding		736,262	756,528	744,126	766,245
Class B [Member]
Net earnings (loss) per share attributable to Berkshire Hathaway shareholders:
Average shares outstanding		1,360,940,890	1,332,192,917	1,350,588,758	1,317,463,821
Insurance and Other [Member]
Revenues:
Insurance premiums earned		$ 14,333	$ 13,349	$ 41,855	$ 47,469
Sales and service revenues		33,249	32,055	98,128	94,017
Interest, dividend and other investment income		1,619	1,320	4,468	3,804
Total revenues		49,201	46,724	144,451	145,290
Costs and expenses:
Insurance losses and loss adjustment expenses		9,932	12,137	28,296	39,450
Life, annuity and health insurance benefits		1,448	1,213	4,153	3,703
Insurance underwriting expenses		2,352	2,207	7,079	6,924
Cost of sales and services		26,789	25,815	78,684	75,594
Selling, general and administrative expenses		3,984	3,965	12,158	12,101
Interest expense and other		116	435	246	1,405
Total costs and expenses		44,621	45,772	130,616	139,177
Railroad, Utilities and Energy [Member]
Revenues:
Total revenues		11,818	10,633	32,815	29,833
Costs and expenses:
Cost of sales and operating expenses		8,087	6,984	23,451	20,678
Interest expense		698	700	2,110	2,090
Total costs and expenses		8,785	7,684	25,561	22,768
Finance and Financial Products [Member]
Revenues:
Sales and service revenues		2,057	1,790	5,742	4,936
Interest, dividend and other investment income		374	360	1,115	1,074
Total revenues		2,431	2,150	6,857	6,010
Costs and expenses:
Cost of sales and services		1,273	1,062	3,519	2,891
Selling, general and administrative expenses		564	531	1,549	1,442
Interest expense		82	98	253	305
Total costs and expenses		$ 1,919	$ 1,691	$ 5,321	$ 4,638

[1] Class B shares are economically equivalent to one-fifteen-hundredth of a Class A share. Accordingly, net earnings per average equivalent Class B share outstanding is equal to one-fifteen-hundredth of the equivalent Class A amount. See Note 19.