Quarterly Financial Data (unaudited) (Net sales and gross profit) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended															12 Months Ended
	Dec. 29, 2012	Sep. 29, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Oct. 01, 2011		Jul. 02, 2011		Apr. 02, 2011		Dec. 29, 2012	Dec. 31, 2011		Jan. 01, 2011
Quarterly Financial Data [Abstract]
Net sales	$ 3,563	$ 3,720		$ 3,474		$ 3,440		$ 3,015		$ 3,312		$ 3,386		$ 3,485		$ 14,197	$ 13,198		$ 12,397
Gross profit	$ 1,176	$ 1,466	[1],[2]	$ 1,439	[1],[3]	$ 1,353	[1],[4]	$ 871	[1],[5]	$ 1,369	[1],[2]	$ 1,464	[1],[3]	$ 1,448	[1],[4]	$ 5,434	$ 5,152	[1]

[1] Amounts differ from previously filed quarterly reports due to adopting new pension and post-retirement benefit plan accountingduring the fourth quarter of 2012. Please refer to Note 1 for further details.

[2] For the quarter ended September 29, 2012, the impact of adopting new pension and post-retirement benefit plan accounting increased gross profit by $24 million, net income attributable to Kellogg Company by $22 million, basic earnings per share by $0.06 and diluted earnings per share by $0.07. For the quarter ended October 1, 2011, the impact of adopting new pension and post-retirement benefit plan accounting increased gross profit by $19 million, net income attributable to Kellogg Company by $11 million, basic earnings per share by $0.02 and diluted earnings per share by $0.03.

[3] For the quarter ended June 30, 2012, the impact of adopting new pension and post-retirement benefit plan accounting increased gross profit by $25 million, net income attributable to Kellogg Company by $23 million, basic earnings per share by $0.07 and diluted earnings per share by $0.06. For the quarter ended July 2, 2011, the impact of adopting new pension and post-retirement benefit plan accounting increased gross profit by $21 million, net income attributable to Kellogg Company by $20 million, basic earnings per share by $0.06 and diluted earnings per share by $0.05.

[4] For the quarter ended March 31, 2012, the impact of adopting new pension and post-retirement benefit plan accounting decreased gross profit by $18 million, net income attributable to Kellogg Company by $7 million and basic and diluted earnings per share by $0.02.For the quarter ended April 2, 2011, the impact of adopting new pension and post-retirement benefit plan accounting increased gross profit by $27 million, net income attributable to Kellogg Company by $31 million, basic earnings per share by $0.09 and diluted earnings per share by $0.08.

[5] For the quarter ended December 31, 2011, the impact of adopting new pension and post-retirement benefit plan accounting decreased gross profit by $363 million, net income attributable to Kellogg Company by $427 million, basic earnings per share by $1.19 and diluted earnings per share by $1.18.