Business segment data - Earnings before income taxes (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Segment Reporting Information [Line Items]
Investment and derivative contract gains (losses)	$ 33,061	$ (66,919)	$ 67,819	$ (68,897)
Equity method investments	511	204	1,199	543
Earnings (loss) before income taxes	45,435	(55,308)	90,187	(48,351)
Operating Businesses [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	11,444	10,224	20,984	18,363
Operating Businesses [Member] | Insurance Group [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	4,525	3,179	8,112	4,755
Operating Businesses [Member] | Insurance Group [Member] | Interest, Dividend and Other Investment Income [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	2,912	2,283	5,297	3,644
Operating Businesses [Member] | Insurance Group [Member] | GEICO [Member] | Insurance Premiums Earned [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	514	(487)	1,217	(665)
Operating Businesses [Member] | Insurance Group [Member] | Berkshire Hathaway Primary Group [Member] | Insurance Premiums Earned [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	272	242	540	334
Operating Businesses [Member] | Insurance Group [Member] | Berkshire Hathaway Reinsurance Group [Member] | Insurance Premiums Earned [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	827	1,141	1,058	1,442
Operating Businesses [Member] | BNSF [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	1,615	2,151	3,264	3,960
Operating Businesses [Member] | Berkshire Hathaway Energy [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	624	591	847	1,304
Operating Businesses [Member] | Pilot [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	186		322
Operating Businesses [Member] | Manufacturing Businesses [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	3,103	3,028	5,714	5,852
Operating Businesses [Member] | McLane [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	129	76	242	158
Operating Businesses [Member] | Service and Retailing [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	1,262	1,199	2,483	2,334
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Investment and derivative contract gains (losses)	33,061	(66,919)	67,819	(68,897)
Interest expense, not allocated to segments	(103)	(100)	(217)	(204)
Equity method investments	511	204	1,199	543
Corporate, Eliminations and Other [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	$ 522	$ 1,283	$ 402	$ 1,844