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Equity method investments - Narrative (Detail)		3 Months Ended		6 Months Ended
Equity method investments - Narrative (Detail)	Oct. 03, 2017 USD ($) Employee Location	Jun. 30, 2019 USD ($) shares	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) shares	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Schedule of Equity Method Investments [Line Items]
Equity method earnings		$ 124,000,000	$ 327,000,000	$ 292,000,000	$ 728,000,000
Pilot Travel Centers LLC, d/b/a Pilot Flying J [Member]
Schedule of Equity Method Investments [Line Items]
Number of locations \| Location	750
Pilot Travel Centers LLC, d/b/a Pilot Flying J [Member] \| Minimum [Member]
Schedule of Equity Method Investments [Line Items]
Number of team members \| Employee	28,000
Pilot Travel Centers LLC, d/b/a Pilot Flying J [Member] \| Maximum [Member]
Schedule of Equity Method Investments [Line Items]
Annual revenues	$ 30,000,000,000
Pilot Travel Centers LLC, d/b/a Pilot Flying J [Member] \| Berkshire Hathaway Inc. (Parent) [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage	38.60%
Pilot Travel Centers LLC, d/b/a Pilot Flying J [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, d/b/a Pilot Flying J [Member]
Schedule of Equity Method Investments [Line Items]
Majority ownership percentage	50.10%
Haslam Family [Member] \| Pilot Travel Centers LLC, d/b/a Pilot Flying J [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, d/b/a Pilot Flying J [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		325,442,152
Equity method investment ownership percentage		26.70%		26.70%
Equity method investments, fair value		$ 10,100,000,000		$ 10,100,000,000		$ 14,000,000,000.0
Equity method investments, carrying value		13,500,000,000		13,500,000,000		13,800,000,000
Equity method earnings					467,000,000
Dividends received				260,000,000	407,000,000
The Kraft Heinz Company [Member] \| Restatement Adjustment
Schedule of Equity Method Investments [Line Items]
Equity method investments, carrying value		$ (34,000,000)		$ (34,000,000)
Berkadia Commercial Mortgage LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment ownership percentage		50.00%		50.00%
Commercial paper outstanding		$ 1,470,000,000		$ 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		$ 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%		50.00%
Berkadia Commercial Mortgage LLC [Member] \| Jefferies Financial Group Inc. [Member] \| Insurance Group [Member]
Schedule of Equity Method Investments [Line Items]
Reimbursement rate from joint venture partner of Company's surety bond claim losses				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%		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%		50.00%
Berkadia Commercial Mortgage LLC, Pilot Travel Centers LLC, d/b/a Pilot Flying J, and Electric Transmission Texas, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments, carrying value		$ 3,700,000,000		$ 3,700,000,000		$ 3,500,000,000
Equity method earnings				$ 314,000,000	$ 261,000,000