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Notes payable and other borrowings - Narrative (Detail) € in Millions, £ in Millions, $ in Millions, ¥ in Billions	1 Months Ended							3 Months Ended		9 Months Ended
	Oct. 31, 2024 USD ($)	Oct. 31, 2024 JPY (¥)	Sep. 30, 2024 USD ($)	Sep. 30, 2024 JPY (¥)	Apr. 30, 2024 USD ($)	Apr. 30, 2024 JPY (¥)	Mar. 31, 2024 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 JPY (¥)	Sep. 30, 2024 EUR (€)	Sep. 30, 2024 GBP (£)	Dec. 31, 2023 USD ($)
Debt Instrument [Line Items]
Notes payable and other borrowings												¥ 1,556.0	€ 5,850	£ 1,750
Line of Credit and Commercial Paper Facilities [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Unused lines of credit available			$ 11,500					$ 11,500		$ 11,500
Line of Credit and Commercial Paper Facilities [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy and Subsidiaries [Member]
Debt Instrument [Line Items]
Unused lines of credit available			10,400					10,400		10,400
Insurance and Other [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings			43,651					43,651		43,651					$ 42,692
Insurance and Other [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Subsidiaries Excluding Berkshire Hathaway Finance Corporation [Member]
Debt Instrument [Line Items]
Guarantee obligation			$ 2,700					$ 2,700		$ 2,700
Insurance and Other [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Weighted average interest rate, percentage			4.50%					4.50%		4.50%		4.50%	4.50%	4.50%
Notes payable and other borrowings			$ 4,603					$ 4,603		$ 4,603					4,696
Insurance and Other [Member] \| Term Debt Due in 2028 [Member] \| Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Debt borrowed			$ 1,000	¥ 142.5
Interest rate during period			1.25%	1.25%
Debt maturity year			2028	2028
Insurance and Other [Member] \| Senior Notes [Member] \| Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Repayments of borrowings										1,900
Insurance and Other [Member] \| Senior Notes [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Berkshire Hathaway Finance Corporation [Member]
Debt Instrument [Line Items]
Gains (loss) attributable to changes in foreign currency exchange rates								(1,500)	$ 582	$ (136)	$ 1,100
Insurance and Other [Member] \| Senior Notes [Member] \| Debt Due 2027 to 2054 [Member] \| Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Principal amount of debt issued					$ 1,700	¥ 263.3
Insurance and Other [Member] \| Senior Notes [Member] \| Debt Due 2027 to 2054 [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Principal amount of debt issued	$ 1,850	¥ 281.8
Insurance and Other [Member] \| Minimum [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Debt maturity year										2024
Insurance and Other [Member] \| Minimum [Member] \| Senior Notes [Member] \| Debt Due 2027 to 2054 [Member] \| Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Interest rate during period					0.974%	0.974%
Debt maturity year					2027	2027
Insurance and Other [Member] \| Minimum [Member] \| Senior Notes [Member] \| Debt Due 2027 to 2054 [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Interest rate during period	1.031%	1.031%
Debt maturity year	2027	2027
Insurance and Other [Member] \| Maximum [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Debt maturity year										2051
Insurance and Other [Member] \| Maximum [Member] \| Senior Notes [Member] \| Debt Due 2027 to 2054 [Member] \| Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Interest rate during period					2.498%	2.498%
Debt maturity year					2054	2054
Insurance and Other [Member] \| Maximum [Member] \| Senior Notes [Member] \| Debt Due 2027 to 2054 [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Interest rate during period	2.625%	2.625%
Debt maturity year	2054	2054
Railroad, Utilities and Energy [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings			$ 80,856					$ 80,856		$ 80,856					85,579
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy Subsidiaries [Member]
Debt Instrument [Line Items]
Weighted average interest rate, percentage			4.60%					4.60%		4.60%		4.60%	4.60%	4.60%
Notes payable and other borrowings			$ 43,452					$ 43,452		$ 43,452					39,072
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Pilot Travel Centers And Subsidiaries [Member]
Debt Instrument [Line Items]
Proceeds from borrowings							$ 5,700
Weighted average interest rate, percentage			0.00%					0.00%		0.00%		0.00%	0.00%	0.00%
Notes payable and other borrowings															$ 5,776
Railroad, Utilities and Energy [Member] \| Term Debt [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy and Subsidiaries [Member]
Debt Instrument [Line Items]
Repayments of borrowings										$ 4,400
Railroad, Utilities and Energy [Member] \| Term Debt [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy Subsidiaries [Member]
Debt Instrument [Line Items]
Principal amount of debt issued										$ 5,400
Weighted average interest rate, percentage			5.40%					5.40%		5.40%		5.40%	5.40%	5.40%
Railroad, Utilities and Energy [Member] \| Senior Notes [Member] \| Debt Due In 2054 [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy Subsidiaries [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Principal amount of debt issued	$ 900
Debt instrument, interest rate, stated percentage	5.60%	5.60%
Debt maturity year	2054	2054
Railroad, Utilities and Energy [Member] \| Senior Unsecured Debentures [Member] \| Subsidiaries [Member] \| BNSF [Member]
Debt Instrument [Line Items]
Repayments of borrowings										$ 1,200
Principal amount of debt issued										$ 1,300
Debt instrument, interest rate, stated percentage			5.50%					5.50%		5.50%		5.50%	5.50%	5.50%
Debt maturity year										2055
Railroad, Utilities and Energy [Member] \| Minimum [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy Subsidiaries [Member]
Debt Instrument [Line Items]
Debt maturity year										2024
Railroad, Utilities and Energy [Member] \| Minimum [Member] \| Term Debt [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy Subsidiaries [Member]
Debt Instrument [Line Items]
Debt maturity year										2029
Railroad, Utilities and Energy [Member] \| Maximum [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy Subsidiaries [Member]
Debt Instrument [Line Items]
Debt maturity year										2064
Railroad, Utilities and Energy [Member] \| Maximum [Member] \| Term Debt [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy Subsidiaries [Member]
Debt Instrument [Line Items]
Debt maturity year										2055