Business segment data - Earnings before income taxes (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Investment and derivative contract gains (losses)	$ (29,778)	$ (13,465)	$ 38,041	$ (82,362)
Equity method investments	262	415	1,461	958
Earnings (loss) before income taxes	(16,959)	(4,258)	73,228	(52,609)
Operating Businesses [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	12,064	7,815	33,048	26,178
Operating Businesses [Member] | Insurance Group [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	5,933	387	14,045	5,142
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	2,933	1,678	8,230	5,322
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	1,053	(759)	2,270	(1,424)
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	510	(281)	1,050	53
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	1,437	(251)	2,495	1,191
Operating Businesses [Member] | BNSF [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	1,608	1,884	4,872	5,844
Operating Businesses [Member] | Berkshire Hathaway Energy [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	(147)	1,347	700	2,651
Operating Businesses [Member] | PTC [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	291		613
Operating Businesses [Member] | Manufacturing Businesses [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	3,077	2,883	8,791	8,735
Operating Businesses [Member] | McLane [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	116	112	358	270
Operating Businesses [Member] | Service and Retailing [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	1,186	1,202	3,669	3,536
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Investment and derivative contract gains (losses)	(29,778)	(13,465)	38,041	(82,362)
Interest expense, not allocated to segments	(100)	(99)	(317)	(303)
Equity method investments	262	415	1,461	958
Corporate, Eliminations and Other [Member]
Segment Reporting Information [Line Items]
Earnings (Loss) Before Income Taxes of Operating Businesses	$ 593	$ 1,076	$ 995	$ 2,920