New accounting pronouncements - Summary of effects from adopting ASU 2018-12 on affected line items consolidated statement of earnings and comprehensive income (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022
Costs and Expenses [Abstract]
Earnings (loss) before income taxes		$ 45,435		$ (55,308)		$ 90,187	$ (48,351)
Income Tax Expense (Benefit)		9,236		(12,066)		18,231	(10,814)
Net earnings (loss)		36,199	$ 35,757	(43,242)	$ 5,705	71,956	(37,537)
Net earnings (loss) attributable to Berkshire Hathaway shareholders		35,912		(43,621)		71,416	(38,041)
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Foreign currency translation		383		(1,750)		632	(2,065)
Long duration insurance contracts				2,147			4,566
Other comprehensive income, net		757	$ 82	372	$ 2,016	839	2,388
Comprehensive income attributable to Berkshire Hathaway shareholders		$ 36,648		$ (43,220)		$ 72,228	$ (35,621)
Equivalent Class A [Member]
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Net earnings (loss) per average equivalent		$ 24,775		$ (29,663)		$ 49,152	$ (25,832)
Equivalent Class B [Member]
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Net earnings (loss) per average equivalent	[1]	$ 16.52		$ (19.78)		$ 32.77	$ (17.22)
Insurance And Other [Member]
Revenues [Abstract]
Insurance premiums earned		$ 20,561		$ 18,081		$ 40,357	$ 35,569
Costs and Expenses [Abstract]
Life, annuity and health insurance benefits		1,128		1,186		1,913	2,523
Insurance underwriting expenses		$ 3,729		2,377		$ 7,316	4,981
Previously Reported [Member]
Costs and Expenses [Abstract]
Earnings (loss) before income taxes				(55,482)			(48,670)
Income Tax Expense (Benefit)				(12,106)			(10,879)
Net earnings (loss)				(43,376)			(37,791)
Net earnings (loss) attributable to Berkshire Hathaway shareholders				(43,755)			(38,295)
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Foreign currency translation				(1,751)			(2,067)
Other comprehensive income, net				(1,776)			(2,180)
Comprehensive income attributable to Berkshire Hathaway shareholders				$ (45,502)			$ (40,443)
Previously Reported [Member] | Equivalent Class A [Member]
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Net earnings (loss) per average equivalent				$ (29,754)			$ (26,005)
Previously Reported [Member] | Equivalent Class B [Member]
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Net earnings (loss) per average equivalent				$ (19.84)			$ (17.34)
Previously Reported [Member] | Insurance And Other [Member]
Revenues [Abstract]
Insurance premiums earned				$ 18,087			$ 35,579
Costs and Expenses [Abstract]
Life, annuity and health insurance benefits				1,282			2,605
Insurance underwriting expenses				2,461			5,228
Revision of Prior Period, Adjustment [Member]
Costs and Expenses [Abstract]
Earnings (loss) before income taxes				174			319
Income Tax Expense (Benefit)				40			65
Net earnings (loss)				134			254
Net earnings (loss) attributable to Berkshire Hathaway shareholders				134			254
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Foreign currency translation				1			2
Long duration insurance contracts				2,147			4,566
Other comprehensive income, net				2,148			4,568
Comprehensive income attributable to Berkshire Hathaway shareholders				$ 2,282			$ 4,822
Revision of Prior Period, Adjustment [Member] | Equivalent Class A [Member]
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Net earnings (loss) per average equivalent				$ 91			$ 173
Revision of Prior Period, Adjustment [Member] | Equivalent Class B [Member]
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Net earnings (loss) per average equivalent				$ 0.06			$ 0.12
Revision of Prior Period, Adjustment [Member] | Insurance And Other [Member]
Revenues [Abstract]
Insurance premiums earned				$ (6)			$ (10)
Costs and Expenses [Abstract]
Life, annuity and health insurance benefits				(96)			(82)
Insurance underwriting expenses				$ (84)			$ (247)

[1] Class B shares are economically equivalent to one-fifteen-hundredth of a Class A share. Accordingly, net earnings per average equivalent Class B share outstanding is equal to one-fifteen-hundredth of the equivalent Class A amount. See Note 19.