Reportable Segments (Supplemental product information) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Jan. 03, 2015	Sep. 27, 2014	Jun. 28, 2014	Mar. 29, 2014	Dec. 28, 2013	Sep. 28, 2013	Jun. 29, 2013	Mar. 30, 2013	Jan. 03, 2015	Dec. 28, 2013	Dec. 29, 2012
Net sales	$ 3,514	$ 3,639	$ 3,685	$ 3,742	$ 3,501	$ 3,716	$ 3,714	$ 3,861	$ 14,580	$ 14,792	$ 14,197
Retail Channel Cereal [Member]
Net sales									6,268	6,451	6,652
Retail Channel Snacks [Member]
Net sales									6,622	6,625	5,891
Frozen And Specialty Channels [Member]
Net sales									$ 1,690	$ 1,716	$ 1,654