Consolidated Statements of Earnings - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenues:
Insurance and other sales and service / Energy operating revenues	$ 49,014	$ 43,494	$ 141,747	$ 122,324
Leasing revenues	1,565	1,316	4,336	3,905
Total revenues	70,583	63,024	204,296	181,129
Investment and derivative contract gains	4,921	31,582	38,015	1,392
Costs and expenses:
Total costs and expenses	63,397	56,966	180,353	172,564
Earnings before income taxes and equity method earnings	12,107	37,640	61,958	9,957
Equity method earnings	377	290	775	333
Earnings before income taxes	12,484	37,930	62,733	10,290
Income tax expense	1,840	7,517	11,824	3,167
Net earnings	10,644	30,413	50,909	7,123
Earnings attributable to noncontrolling interests	300	276	760	437
Net earnings attributable to Berkshire Hathaway shareholders	$ 10,344	$ 30,137	$ 50,149	$ 6,686
Equivalent Class A [Member]
Costs and expenses:
Net earnings per average equivalent share	$ 6,882	$ 18,994	$ 33,025	$ 4,160
Average equivalent shares outstanding	1,503,013	1,586,698	1,518,513	1,607,041
Equivalent Class B [Member]
Costs and expenses:
Net earnings per average equivalent share	$ 4.59	$ 12.66	$ 22.02	$ 2.77
Average equivalent shares outstanding	2,254,518,838	2,380,046,304	2,277,769,582	2,410,561,550
Insurance and Other [Member]
Revenues:
Insurance premiums earned	$ 17,727	$ 15,913	$ 51,314	$ 47,256
Insurance and other sales and service / Energy operating revenues	36,722	32,703	107,163	93,332
Leasing revenues	1,565	1,316	4,336	3,905
Interest, dividend and other investment income	1,795	1,717	5,544	6,143
Total revenues	57,809	51,649	168,357	150,636
Costs and expenses:
Insurance losses and loss adjustment expenses	13,939	11,667	37,078	32,712
Life, annuity and health insurance benefits	1,568	1,311	4,507	4,101
Insurance underwriting expenses	3,239	3,228	9,318	9,219
Cost of sales and services	28,984	25,957	84,275	74,565
Cost of leasing	1,116	854	2,980	2,605
Selling, general and administrative expenses	4,889	5,181	13,844	14,304
Goodwill and intangible asset impairments		25		10,659
Interest expense	286	263	860	817
Total costs and expenses	54,021	48,486	152,862	148,982
Freight Rail Transportation [Member]
Revenues:
Total revenues	5,761	5,148	16,917	15,101
Costs and expenses:
Expenses	3,527	3,161	10,625	9,625
Utilities and Energy [Member]
Revenues:
Insurance and other sales and service / Energy operating revenues	5,225	4,451	14,375	11,504
Costs and expenses:
Cost of sales and other expenses	3,497	3,101	10,306	8,326
Railroad, Utilities and Energy [Member]
Revenues:
Service revenues and other income	1,788	1,776	4,647	3,888
Total revenues	12,774	11,375	35,939	30,493
Costs and expenses:
Other expenses	1,582	1,481	4,238	3,422
Interest expense	770	737	2,322	2,209
Total costs and expenses	$ 9,376	$ 8,480	$ 27,491	$ 23,582