Equity - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jul. 02, 2016	Jul. 04, 2015	Jul. 02, 2016	Jul. 04, 2015
Equity [Abstract]
Net income attributable to Kellogg Company, Basic	$ 280	$ 223	$ 455	$ 450
Average shares outstanding, Basic (in shares)	350	353	350	354
Earnings per share, Basic (in dollars per share)	$ 0.80	$ 0.63	$ 1.30	$ 1.27
Average shares outstanding, Dilutive potential common shares (in shares)	4	2	4	2
Earnings per share, Dilutive potential common shares (in dollars per share)	$ (0.01)	$ 0.00	$ (0.01)	$ (0.01)
Net income attributable to Kellogg Company, Diluted	$ 280	$ 223	$ 455	$ 450
Average shares outstanding, Diluted (in shares)	354	355	354	356
Earnings per share, Diluted (in dollars per share)	$ 0.79	$ 0.63	$ 1.29	$ 1.26