Equity Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Jan. 02, 2016	Oct. 03, 2015	Jul. 04, 2015	Apr. 04, 2015	Jan. 03, 2015	Sep. 27, 2014	Jun. 28, 2014	Mar. 29, 2014	Jan. 02, 2016	Jan. 03, 2015	Dec. 28, 2013
Equity [Abstract]
Net income (loss) attributable to Kellogg Company, Basic	$ (41)	$ 205	$ 223	$ 227	$ (293)	$ 224	$ 295	$ 406	$ 614	$ 632	$ 1,807
Average shares outstanding, Basic (in shares)									354	358	363
Earnings per share, Basic (in shares)	$ (0.12)	$ 0.58	$ 0.63	$ 0.64	$ (0.82)	$ 0.63	$ 0.82	$ 1.13	$ 1.74	$ 1.76	$ 4.98
Average shares outstanding, Dilutive potential common shares (in shares)									2	2	2
Earnings per share, Dilutive potential common shares (in dollars per share)									$ (0.02)	$ (0.01)	$ (0.04)
Net income attributed to Kellogg Company, Diluted									$ 614	$ 632	$ 1,807
Average shares outstanding, Diluted (in shares)									356	360	365
Earnings per share, Diluted (in dollars per share)	$ (0.12)	$ 0.58	$ 0.63	$ 0.64	$ (0.82)	$ 0.62	$ 0.82	$ 1.12	$ 1.72	$ 1.75	$ 4.94