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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
	Apr. 30, 2025 USD ($)	Apr. 30, 2025 JPY (¥)	Mar. 31, 2025 USD ($)	Mar. 31, 2024 USD ($)	Mar. 31, 2025 JPY (¥)	Mar. 31, 2025 EUR (€)	Mar. 31, 2025 GBP (£)	Dec. 31, 2024 USD ($)
Berkshire Hathaway Inc. (Parent) [Member] \| Berkshire Hathaway Finance Corporation [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings					¥ 1,988.0	€ 4,850	£ 1,750
Line of Credit and Commercial Paper Facilities [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Unused and available lines of credit			$ 11,700
Line of Credit and Commercial Paper Facilities [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy and Subsidiaries [Member]
Debt Instrument [Line Items]
Unused and available lines of credit			10,600
Insurance and Other [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings			44,461					$ 44,885
Insurance and Other [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Subsidiaries Excluding Berkshire Hathaway Finance Corporation [Member]
Debt Instrument [Line Items]
Guarantee obligation			$ 2,700
Insurance and Other [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Weighted average interest rate, percentage			4.40%		4.40%	4.40%	4.40%
Notes payable and other borrowings			$ 4,551					4,564
Insurance and Other [Member] \| Senior Notes [Member] \| Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Repayments of borrowings			1,300
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			$ 936	$ 781
Insurance and Other [Member] \| Senior Notes [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Debt Due 2028 to 2055 [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Repayments of borrowings	$ 289	¥ 41.6
Principal amount of debt issued	$ 632	¥ 90.0
Interest rate during period	1.637%	1.637%
Insurance and Other [Member] \| Minimum [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Debt maturity year			2025
Insurance and Other [Member] \| Minimum [Member] \| Senior Notes [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Debt Due 2028 to 2055 [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Debt maturity year	2028	2028
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] \| Berkshire Hathaway Inc. (Parent) [Member] \| Debt Due 2028 to 2055 [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Debt maturity year	2055	2055
Railroad, Utilities and Energy [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings			$ 81,466					79,877
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy Subsidiaries [Member]
Debt Instrument [Line Items]
Weighted average interest rate, percentage			4.70%		4.70%	4.70%	4.70%
Notes payable and other borrowings			$ 44,579					$ 42,150
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Term Debt [Member] \| Berkshire Hathaway Energy Subsidiaries [Member]
Debt Instrument [Line Items]
Repayments of borrowings			890
Principal amount of debt issued			$ 2,400
Weighted average interest rate, percentage			6.50%		6.50%	6.50%	6.50%
Railroad, Utilities and Energy [Member] \| Minimum [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy Subsidiaries [Member]
Debt Instrument [Line Items]
Debt maturity year			2025
Railroad, Utilities and Energy [Member] \| Minimum [Member] \| Subsidiaries [Member] \| Term Debt [Member] \| Berkshire Hathaway Energy Subsidiaries [Member]
Debt Instrument [Line Items]
Debt maturity year			2035
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] \| Subsidiaries [Member] \| Term Debt [Member] \| Berkshire Hathaway Energy Subsidiaries [Member]
Debt Instrument [Line Items]
Debt maturity year			2055