Business segment data - Earnings (loss) before income taxes (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting Information [Line Items]
Investment and derivative contract gains (losses)	$ (13,465)	$ 4,921	$ (82,362)	$ 38,015
Equity method investments	441	377	1,048	775
Earnings (loss) before income taxes	(4,117)	12,484	(52,787)	62,733
Operating Businesses [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	7,930	7,268	25,910	24,088
Operating Businesses [Member] \| Insurance Group [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	528	317	4,964	4,616
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	1,678	1,337	5,322	4,205
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	(759)	(289)	(1,424)	1,360
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	(110)	(708)	1,013	(1,298)
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	(281)	(23)	53	349
Operating Businesses [Member] \| BNSF [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	1,884	2,029	5,844	5,667
Operating Businesses [Member] \| Berkshire Hathaway Energy [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	1,321	1,375	2,561	2,797
Operating Businesses [Member] \| Manufacturing Businesses [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	2,883	2,445	8,735	7,595
Operating Businesses [Member] \| McLane [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	112	(8)	270	179
Operating Businesses [Member] \| Service and Retailing [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	1,202	1,110	3,536	3,234
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Investment and derivative contract gains (losses)	(13,465)	4,921	(82,362)	38,015
Interest expense, not allocated to segments	(99)	(128)	(303)	(386)
Equity method investments	441	377	1,048	775
Corporate, Eliminations and Other [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	$ 1,076	$ 46	$ 2,920	$ 241

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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