Reportable Segments Supplemental Product Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 01, 2022	Oct. 02, 2021	Oct. 01, 2022	Oct. 02, 2021
Segment Reporting Information [Line Items]
Net sales	$ 3,946	$ 3,622	$ 11,482	$ 10,761
Snacks
Segment Reporting Information [Line Items]
Net sales	1,943	1,712	5,635	5,015
Cereal
Segment Reporting Information [Line Items]
Net sales	1,355	1,313	3,978	4,023
Frozen
Segment Reporting Information [Line Items]
Net sales	281	277	829	841
Noodles and other
Segment Reporting Information [Line Items]
Net sales	$ 367	$ 320	$ 1,040	$ 882