Equity method investments - Summary of carrying value and fair value of investments (Detail) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Schedule of Equity Method Investments [Line Items]
Carrying Value	$ 31,144	$ 31,134
Kraft Heinz [Member]
Schedule of Equity Method Investments [Line Items]
Carrying Value	13,523	13,395
Fair Value	9,903	9,994
Occidental [Member]
Schedule of Equity Method Investments [Line Items]
Carrying Value	17,165	17,287
Fair Value	13,078	13,053
Berkadia [Member]
Schedule of Equity Method Investments [Line Items]
Carrying Value	$ 456	$ 452