Consolidated Statements of Earnings - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Sales and service revenues		$ 166,733	$ 176,512	$ 175,445
Leasing revenues		5,209	5,856
Total revenues		245,510	254,616	247,837
Investment and derivative contract gains/losses:		40,746	72,607	(22,455)
Costs and expenses:
Interest expense		4,083	3,961	3,853
Total costs and expenses		231,289	225,703	219,214
Earnings before income taxes and equity method earnings (losses)		54,967	101,520	6,168
Equity method earnings (losses)		726	1,176	(2,167)
Earnings before income taxes		55,693	102,696	4,001
Income tax expense (benefit)		12,440	20,904	(321)
Net earnings		43,253	81,792	4,322
Earnings attributable to noncontrolling interests		732	375	301
Net earnings attributable to Berkshire Hathaway shareholders		$ 42,521	$ 81,417	$ 4,021
Equivalent Class A [Member]
Costs and expenses:
Net earnings per average equivalent share		$ 26,668	$ 49,828	$ 2,446
Average equivalent shares outstanding		1,594,469	1,633,946	1,643,795
Equivalent Class B [Member]
Costs and expenses:
Net earnings per average equivalent share	[1]	$ 17.78	$ 33.22	$ 1.63
Average equivalent shares outstanding		2,391,703,454	2,450,919,020	2,465,692,368
Insurance and Other [Member]
Revenues:
Insurance premiums earned		$ 63,401	$ 61,078	$ 57,418
Sales and service revenues		127,044	134,989	133,336
Leasing revenues		5,209	5,856	5,732
Interest, dividend and other investment income		8,092	9,240	7,678
Total revenues		203,746	211,163	204,164
Costs and expenses:
Insurance losses and loss adjustment expenses		43,951	44,456	39,906
Life, annuity and health insurance benefits		5,812	4,986	5,699
Insurance underwriting expenses		12,798	11,200	9,793
Cost of sales and services		101,091	107,041	106,083
Cost of leasing		3,520	4,003	4,061
Selling, general and administrative expenses		19,809	19,226	17,856
Goodwill and intangible asset impairments		10,671	96	382
Interest expense		1,105	1,056	1,035
Total costs and expenses		198,757	192,064	184,815
Freight Rail Transportation [Member]
Revenues:
Total revenues		20,750	23,357	23,703
Costs and expenses:
Expenses		13,120	15,436	16,045
Utilities and Energy [Member]
Revenues:
Sales and service revenues		15,540	15,353	15,555
Costs and expenses:
Cost of sales and other expenses		11,638	11,296	11,641
Railroad, Utilities and Energy [Member]
Revenues:
Service revenues and other income		5,474	4,743	4,415
Total revenues		41,764	43,453	43,673
Costs and expenses:
Other expenses		4,796	4,002	3,895
Interest expense		2,978	2,905	2,818
Total costs and expenses		$ 32,532	$ 33,639	$ 34,399

[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.