Reportable Segments Supplemental product information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Jul. 02, 2016	Apr. 02, 2016	Jan. 02, 2016	Oct. 03, 2015	Jul. 04, 2015	Apr. 04, 2015	Dec. 31, 2016	Jan. 02, 2016	Jan. 03, 2015
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net	$ 3,097	$ 3,254	$ 3,268	$ 3,395	$ 3,142	$ 3,329	$ 3,498	$ 3,556	$ 13,014	$ 13,525	$ 14,580
Cereal [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net									5,440	5,871	6,570
Snacks [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net									6,660	6,698	7,002
Frozen [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net									$ 914	$ 956	$ 1,008