Reportable Segments Supplemental Product Information (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 01, 2023	Apr. 02, 2022
Segment Reporting Information [Line Items]
Net sales	$ 4,053	$ 3,672
Snacks
Segment Reporting Information [Line Items]
Net sales	2,022	1,775
Cereal
Segment Reporting Information [Line Items]
Net sales	1,390	1,281
Frozen
Segment Reporting Information [Line Items]
Net sales	292	291
Noodles and other
Segment Reporting Information [Line Items]
Net sales	$ 349	$ 325