Business segment data - Earnings (loss) before income taxes (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Investment and derivative contract gains (losses)	$ (1,978)	$ 5,700
Equity method investments	376	251
Earnings (loss) before income taxes	6,812	14,528
Operating Businesses [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	7,957	8,197
Operating Businesses [Member] \| Insurance Group [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	1,431	2,378
Operating Businesses [Member] \| Insurance Group [Member] \| Interest, Dividend and Other Investment Income [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	1,361	1,412
Operating Businesses [Member] \| Insurance Group [Member] \| GEICO [Member] \| Insurance Premiums Earned [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	(178)	1,023
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 from operating businesses	156	(263)
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 from operating businesses	92	206
Operating Businesses [Member] \| BNSF [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	1,809	1,659
Operating Businesses [Member] \| Berkshire Hathaway Energy [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	676	683
Operating Businesses [Member] \| Manufacturing Businesses [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	2,824	2,436
Operating Businesses [Member] \| McLane [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	82	103
Operating Businesses [Member] \| Service and Retailing [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	1,135	938
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Investment and derivative contract gains (losses)	(1,978)	5,700
Interest expense, not allocated to segments	(104)	(114)
Equity method investments	376	251
Corporate, Eliminations and Other [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	$ 561	$ 494

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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