Reportable Segments Supplemental product information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 30, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 31, 2016	Oct. 01, 2016	Jul. 02, 2016	Apr. 02, 2016	Dec. 30, 2017	Dec. 31, 2016	Jan. 02, 2016
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net	$ 3,209	$ 3,273	$ 3,187	$ 3,254	$ 3,097	$ 3,254	$ 3,268	$ 3,395	$ 12,923	$ 13,014	$ 13,525
Snacks [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net									6,700	6,660	6,698
Retail Channel Cereal [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net									5,270	5,440	5,871
Frozen [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net									$ 953	$ 914	$ 956