Consolidated Statements of Earnings - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Revenues:
Sales and service revenues		$ 41,509
Total revenues		58,473	$ 64,370
Investment and derivative contract gains/losses:
Investments gains (losses)		(7,809)	315
Derivative contract gains (losses)		(206)	460
Investment and derivative gains/losses		(8,015)	775
Costs and expenses:
Total costs and expenses		52,382	59,738
Earnings (loss) before income taxes and equity method earnings		(1,924)	5,407
Equity method earnings		401	281
Earnings (loss) before income taxes		(1,523)	5,688
Income tax expense (benefit)		(452)	1,549
Net earnings (loss)		(1,071)	4,139
Earnings attributable to noncontrolling interests		67	79
Net earnings (loss) attributable to Berkshire Hathaway shareholders		$ (1,138)	$ 4,060
Equivalent Class A [Member]
Net earnings (loss) per share attributable to Berkshire Hathaway shareholders:
Net earnings (loss) per share attributable to Berkshire Hathaway shareholders		$ (692)	$ 2,469
Average equivalent shares outstanding		1,644,958	1,644,425
Equivalent Class B [Member]
Net earnings (loss) per share attributable to Berkshire Hathaway shareholders:
Net earnings (loss) per share attributable to Berkshire Hathaway shareholders	[1]	$ (0.46)	$ 1.65
Average equivalent shares outstanding		2,467,436,888	2,466,636,938
Insurance and Other [Member]
Revenues:
Insurance premiums earned		$ 13,373	$ 21,753
Sales and service revenues		31,623	30,229
Interest, dividend and other investment income		1,315	1,162
Total revenues		46,311	53,144
Costs and expenses:
Insurance losses and loss adjustment expenses		8,963	18,566
Life, annuity and health insurance benefits		1,287	1,227
Insurance underwriting expenses		2,604	2,339
Cost of sales and services		25,415	24,360
Selling, general and administrative expenses		4,024	4,116
Interest expense		390	270
Total costs and expenses		42,683	50,878
Railroad, Utilities and Energy [Member]
Revenues:
Total revenues		10,102	9,378
Costs and expenses:
Cost of sales and operating expenses		7,401	6,754
Interest expense		710	693
Total costs and expenses		8,111	7,447
Finance and Financial Products [Member]
Revenues:
Sales and service revenues		1,693	1,498
Interest, dividend and other investment income		367	350
Total revenues		2,060	1,848
Costs and expenses:
Cost of sales and services		1,029	867
Selling, general and administrative expenses		467	442
Interest expense		92	104
Total costs and expenses		$ 1,588	$ 1,413

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