Equity method investments - Narrative (Detail) - USD ($)		3 Months Ended
	Jan. 31, 2023	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Schedule Of Equity Method Investments [Line Items]
Equity method investments		$ 29,585,000,000		$ 29,066,000,000
Equity method earnings		$ 493,000,000	$ 688,000,000
The Kraft Heinz Company [Member]
Schedule Of Equity Method Investments [Line Items]
Equity method investment ownership percentage		26.80%
Percentage of excess of carrying values over fair values of investments		9.50%
Equity method investments		$ 13,274,000,000		13,230,000,000
Equity method earnings		$ 215,000,000	222,000,000
Occidental Petroleum Corporation [Member]
Schedule Of Equity Method Investments [Line Items]
Equity method investment ownership percentage		28.20%
Equity method investments		$ 15,873,000,000		15,410,000,000
Equity method earnings		$ 263,000,000	$ 370,000,000
Occidental Petroleum Corporation [Member] | Common Stock [Member]
Schedule Of Equity Method Investments [Line Items]
Excess of carrying value of investment over investees equity				$ 9,700,000,000
Berkadia Commercial Mortgage LLC [Member]
Schedule Of Equity Method Investments [Line Items]
Equity method investment ownership percentage		50.00%
Berkadia Commercial Mortgage LLC [Member] | Jefferies Financial Group Inc. [Member]
Schedule Of Equity Method Investments [Line Items]
Equity method investment ownership percentage		50.00%
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
Pilot Travel Centers LLC [Member]
Schedule Of Equity Method Investments [Line Items]
Equity method earnings	$ 105,000,000