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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		6 Months Ended
	Jul. 31, 2025 USD ($)	Jul. 31, 2025 JPY (¥)	Apr. 30, 2025 USD ($)	Apr. 30, 2025 JPY (¥)	Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2025 JPY (¥)	Jun. 30, 2025 EUR (€)	Jun. 30, 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									¥ 2,036.0	€ 4,850	£ 1,750
Line of Credit and Commercial Paper Facilities [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Unused and available lines of credit					$ 11,000		$ 11,000
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					9,800		9,800
Insurance and Other [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings					45,040		45,040					$ 44,885
Insurance and Other [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Subsidiaries Excluding Berkshire Hathaway Finance Corporation [Member]
Debt Instrument [Line Items]
Guarantee obligation					1,700		1,700
Insurance and Other [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Short-term borrowings					$ 1,299		$ 1,299					1,315
Weighted average interest rate, percentage					5.00%		5.00%		5.00%	5.00%	5.00%
Notes payable and other borrowings					$ 3,572		$ 3,572					4,564
Insurance and Other [Member] \| Senior Notes [Member] \| Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Repayments of borrowings							1,600
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					(1,200)	$ 588	$ (2,100)	$ 1,400
Insurance and Other [Member] \| Senior Notes [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Debt Due 2028 to 2055 [Member]
Debt Instrument [Line Items]
Principal amount of debt issued			$ 632	¥ 90.0
Interest rate during period			1.637%	1.637%
Insurance and Other [Member] \| Senior Notes [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Debt Due 2030 to 2040 [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Principal amount of debt issued	$ 1,000	¥ 151.5
Interest rate during period	2.306%	2.306%
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]
Debt Instrument [Line Items]
Debt maturity year			2028	2028
Insurance and Other [Member] \| Minimum [Member] \| Senior Notes [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Debt Due 2030 to 2040 [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Debt maturity year	2030	2030
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]
Debt Instrument [Line Items]
Debt maturity year			2055	2055
Insurance and Other [Member] \| Maximum [Member] \| Senior Notes [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Debt Due 2030 to 2040 [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Debt maturity year	2040	2040
Railroad, Utilities and Energy [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings					81,980		$ 81,980					79,877
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy and Subsidiaries [Member]
Debt Instrument [Line Items]
Short-term borrowings					$ 1,687		$ 1,687					1,123
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%	4.70%
Notes payable and other borrowings					$ 44,982		$ 44,982					$ 42,150
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Term Debt [Member] \| Berkshire Hathaway Energy Subsidiaries [Member]
Debt Instrument [Line Items]
Repayments of borrowings							2,000
Short-term borrowings					$ 564		564
Principal amount of debt issued							$ 2,700
Weighted average interest rate, percentage					6.50%		6.50%		6.50%	6.50%	6.50%
Railroad, Utilities and Energy [Member] \| Senior Unsecured Debentures [Member] \| Subsidiaries [Member] \| BNSF [Member]
Debt Instrument [Line Items]
Repayments of borrowings							$ 530
Principal amount of debt issued							$ 900
Debt instrument, interest rate, stated percentage					5.80%		5.80%		5.80%	5.80%	5.80%
Debt maturity year							2056
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