Accounting Policies (Pension and Nonpension) (Details) (USD $) In Millions, except Per Share data, 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
Consolidated Statement of Income
Cost of goods sold																$ 8,763	$ 8,046	$ 7,055
Selling, general and administrative expense																3,872	3,725	3,305
Operating profit																1,562	1,427	2,037
Income before taxes																1,325	1,184	1,790
Income taxes																363	320	510
Net income																961	864	1,280
Net income attributable to Kellogg Company	(32)	318	[1],[2]	324	[1],[3]	351	[1],[4]	(195)	[1],[5]	301	[1],[2]	363	[1],[3]	397	[1],[4]	961	866	1,287
Per share amounts:
Basic EPS	$ (0.09)	$ 0.89	[1],[2]	$ 0.91	[1],[3]	$ 0.98	[1],[4]	$ (0.54)	[1],[5]	$ 0.83	[1],[2]	$ 1.00	[1],[3]	$ 1.09	[1],[4]	$ 2.68	$ 2.39	$ 3.43
Diluted EPS	$ (0.09)	$ 0.89	[1],[2]	$ 0.90	[1],[3]	$ 0.98	[1],[4]	$ (0.54)	[1],[5]	$ 0.83	[1],[2]	$ 0.99	[1],[3]	$ 1.08	[1],[4]	$ 2.67	$ 2.38	$ 3.40
Consolidated Balance Sheet
Inventory, Net	1,365							1,174								1,365	1,174
Deferred income taxes current	152							149								152	149
Retained earnings	5,615							5,305								5,615	5,305
Accumulated other comprehensive income (loss)	(931)							(1,006)								(931)	(1,006)
Retained earnings:
Retained Earnings (Accumulated Deficit), Beginning Balance						5,305										5,305
Net income	(32)	318	[1],[2]	324	[1],[3]	351	[1],[4]	(195)	[1],[5]	301	[1],[2]	363	[1],[3]	397	[1],[4]	961	866	1,287
Retained Earnings (Accumulated Deficit), Ending Balance	5,615							5,305								5,615	5,305
Accumulated other comprehensive income (loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning Balance						(1,006)										(1,006)
Other comprehensive income (loss)																75	(136)	22
Accumulated Other Comprehensive Income (Loss), Net of Tax, Ending Balance	(931)							(1,006)								(931)	(1,006)
Operating activities
Net income																961	864	1,280
Deferred income taxes																(159)	(93)	266
Other																(21)	(115)	3
Inventories																(80)	(125)	(159)
Net Cash Provided by (Used in) Operating Activities																1,758	1,595	1,008
Previously Reported
Consolidated Statement of Income
Cost of goods sold																	7,750	7,108
Selling, general and administrative expense																	3,472	3,299
Operating profit																	1,976	1,990
Income before taxes																	1,732	1,742
Income taxes																	503	502
Net income																	1,229	1,240
Net income attributable to Kellogg Company																	1,231	1,247
Per share amounts:
Basic EPS																	$ 3.40	$ 3.32
Diluted EPS																	$ 3.38	$ 3.30
Consolidated Balance Sheet
Inventory, Net								1,132									1,132
Deferred income taxes current								637									637
Retained earnings								6,721									6,721	6,122
Accumulated other comprehensive income (loss)								(2,458)									(2,458)	(1,914)
Retained earnings:
Retained Earnings (Accumulated Deficit), Beginning Balance														6,122			6,122	5,481
Net income																	1,231	1,247
Retained Earnings (Accumulated Deficit), Ending Balance								6,721									6,721	6,122
Accumulated other comprehensive income (loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning Balance														(1,914)			(1,914)	(1,966)
Other comprehensive income (loss)																	(544)	52
Accumulated Other Comprehensive Income (Loss), Net of Tax, Ending Balance								(2,458)									(2,458)	(1,914)
Operating activities
Net income																	1,229	1,240
Postretirement benefit expense																	0	0
Deferred income taxes																	84	266
Other																	(22)	97
Inventories																	(76)	(146)
Net Cash Provided by (Used in) Operating Activities																	1,595	1,008
Re-Cast
Consolidated Statement of Income
Cost of goods sold																	8,046	7,055
Selling, general and administrative expense																	3,725	3,305
Operating profit																	1,427	2,037
Income before taxes																	1,184	1,790
Income taxes																	320	510
Net income																	864	1,280
Net income attributable to Kellogg Company																	866	1,287
Per share amounts:
Basic EPS																	$ 2.39	$ 3.43
Diluted EPS																	$ 2.38	$ 3.40
Consolidated Balance Sheet
Inventory, Net								1,174									1,174
Deferred income taxes current								643									643
Retained earnings								5,305									5,305	5,071
Accumulated other comprehensive income (loss)								(1,006)									(1,006)	(870)
Retained earnings:
Retained Earnings (Accumulated Deficit), Beginning Balance														5,071			5,071	4,390
Net income																	866	1,287
Retained Earnings (Accumulated Deficit), Ending Balance								5,305									5,305	5,071
Accumulated other comprehensive income (loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning Balance														(870)			(870)	(892)
Other comprehensive income (loss)																	(136)	22
Accumulated Other Comprehensive Income (Loss), Net of Tax, Ending Balance								(1,006)									(1,006)	(870)
Operating activities
Net income																	864	1,280
Postretirement benefit expense																	684	67
Deferred income taxes																	(93)	266
Other																	(115)	3
Inventories																	(125)	(159)
Net Cash Provided by (Used in) Operating Activities																	1,595	1,008
Effect of Change
Consolidated Statement of Income
Cost of goods sold																168	296	(53)
Selling, general and administrative expense																155	253	6
Operating profit																(323)	(549)	47
Income before taxes																(323)	(548)	48
Income taxes																(105)	(183)	8
Net income																(218)	(365)	40
Net income attributable to Kellogg Company																(218)	(365)	40
Per share amounts:
Basic EPS																$ (0.61)	$ (1.01)	$ 0.11
Diluted EPS																$ (0.61)	$ (1.00)	$ 0.10
Consolidated Balance Sheet
Inventory, Net								42									42
Deferred income taxes current								6									6
Retained earnings								(1,416)									(1,416)	(1,051)
Accumulated other comprehensive income (loss)								1,452									1,452	1,044
Retained earnings:
Retained Earnings (Accumulated Deficit), Beginning Balance						(1,416)								(1,051)		(1,416)	(1,051)	(1,091)
Net income																(218)	(365)	40
Retained Earnings (Accumulated Deficit), Ending Balance								(1,416)									(1,416)	(1,051)
Accumulated other comprehensive income (loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning Balance						1,452								1,044		1,452	1,044	1,074
Other comprehensive income (loss)																	408	(30)
Accumulated Other Comprehensive Income (Loss), Net of Tax, Ending Balance								1,452									1,452	1,044
Operating activities
Net income																(218)	(365)	40
Postretirement benefit expense																	684	67
Deferred income taxes																	(177)	0
Other																	(93)	(94)
Inventories																	(49)	(13)
Net Cash Provided by (Used in) Operating Activities																	0	0
Before Accounting Change [Member]
Consolidated Statement of Income
Cost of goods sold																8,595
Selling, general and administrative expense																3,717
Operating profit																1,885
Income before taxes																1,648
Income taxes																468
Net income																1,179
Net income attributable to Kellogg Company																1,179
Per share amounts:
Basic EPS																$ 3.29
Diluted EPS																$ 3.28
Retained earnings:
Net income																1,179
Operating activities
Net income																1,179
As Reported [Member]
Consolidated Statement of Income
Cost of goods sold																8,763
Selling, general and administrative expense																3,872
Operating profit																1,562
Income before taxes																1,325
Income taxes																363
Net income																961
Net income attributable to Kellogg Company																961
Per share amounts:
Basic EPS																$ 2.68
Diluted EPS																$ 2.67
Retained earnings:
Net income																961
Operating activities
Net income																$ 961

[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.