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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Equity method investments - Narrative (Detail)		12 Months Ended
Equity method investments - Narrative (Detail)	Oct. 03, 2017	Dec. 31, 2020 USD ($) Store Location shares gal	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Schedule of Equity Method Investments [Line Items]
Equity method investment ownership percentage		20.00%
Equity method earnings (losses)		$ 726,000,000	$ 1,176,000,000	$ (2,167,000,000)
Berkshire Hathaway Inc. (Parent) [Member]
Schedule of Equity Method Investments [Line Items]
Equity method earnings (losses)		95,000,000	493,000,000	(2,730,000,000)
Equity method investments, carrying value		$ 13,336,000,000	13,757,000,000
Pilot Travel Centers LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of retail \| Store		950
Pilot Travel Centers LLC [Member] \| U.S. States [Member]
Schedule of Equity Method Investments [Line Items]
Number of fueling locations \| Location		44
Pilot Travel Centers LLC [Member] \| Canadian Provinces [Member]
Schedule of Equity Method Investments [Line Items]
Number of fueling locations \| Location		6
Pilot Travel Centers LLC [Member] \| Minimum [Member]
Schedule of Equity Method Investments [Line Items]
Gallons of fuel purchased annually \| gal		11,000,000,000
Pilot Travel Centers LLC [Member] \| Berkshire Hathaway Inc. (Parent) [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage	38.60%
Pilot Travel Centers LLC [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Agreement to Acquire Additional Interest in 2023 [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of additional interest to be acquired		41.40%
Haslam Family [Member] \| Pilot Travel Centers LLC [Member]
Schedule of Equity Method Investments [Line Items]
Majority ownership percentage		50.10%
Haslam Family [Member] \| Pilot Travel Centers LLC [Member] \| Agreement to Acquire Additional Interest in 2023 [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage		20.00%
Third Party [Member] \| Pilot Travel Centers LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage		11.30%
The Kraft Heinz Company [Member]
Schedule of Equity Method Investments [Line Items]
Number of shares owned \| shares		325,442,152
Equity method investment ownership percentage		26.60%
Equity method earnings (losses)		$ 95,000,000	493,000,000	(2,700,000,000)
Equity method investee, impairment charges		850,000,000	450,000,000	3,700,000,000
Common stock dividends received		521,000,000	521,000,000	814,000,000
Equity method investments, fair value		11,300,000,000	10,500,000,000
Equity method investments, carrying value		13,300,000,000	13,800,000,000
Amount of difference between carrying value and fair value based on quoted market price		$ 2,000,000,000.0
Difference between carrying value and fair value percentage		15.00%
Berkadia Commercial Mortgage LLC, Pilot Travel Centers LLC, and Electric Transmission Texas, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method earnings (losses)		$ 631,000,000	683,000,000	$ 563,000,000
Equity method investments, carrying value		$ 4,000,000,000.0	$ 3,700,000,000
Berkadia Commercial Mortgage LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment ownership percentage		50.00%
Commercial paper outstanding		$ 1,470,000,000
Berkadia Commercial Mortgage LLC [Member] \| Commercial Paper [Member]
Schedule of Equity Method Investments [Line Items]
Maximum outstanding balance of commercial paper borrowings		$ 1,500,000,000
Berkadia Commercial Mortgage LLC [Member] \| Jefferies Financial Group Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment ownership percentage		50.00%
Electric Transmission Texas, LLC [Member] \| Berkshire Hathaway Energy Company Subsidiary [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment ownership percentage		50.00%
Electric Transmission Texas, LLC [Member] \| American Electric Power [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment ownership percentage		50.00%