Equity method investments - Unaudited financial information (Detail) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 29, 2024	Dec. 31, 2023	Dec. 30, 2023	Sep. 30, 2023
Schedule Of Equity Method Investments [Line Items]
Assets	$ 1,108,860				$ 1,108,860					$ 1,069,978
Liabilities	500,889				500,889					$ 499,208
Sales/ Total revenues and other income	93,653		$ 92,503		183,522		$ 177,896
The Kraft Heinz Company [Member]
Schedule Of Equity Method Investments [Line Items]
Assets									$ 88,797		$ 90,339
Liabilities									$ 39,766		$ 40,617
Sales/ Total revenues and other income	6,476		6,721		12,887		13,210
Net earnings attributable to common shareholders	$ 102		$ 1,000		$ 903		$ 1,836
Occidental Petroleum Corporation [Member]
Schedule Of Equity Method Investments [Line Items]
Assets		$ 74,277				$ 74,277						$ 71,287
Liabilities		43,310				43,310						$ 42,515
Sales/ Total revenues and other income		6,010		$ 7,258		13,539		$ 15,584
Net earnings attributable to common shareholders		$ 718		$ 983		$ 1,747		$ 2,710