Reportable Segments (Reportable Segment Information) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 29, 2012	Oct. 01, 2011	Sep. 29, 2012	Oct. 01, 2011
Segment Reporting Information [Line Items]
Net sales	$ 3,720	$ 3,312	$ 10,634	$ 10,183
Operating profit	479	464	1,499	1,579
Reportable segments information			The Company currently manages its operations through nine operating segments that are based on product category or geographic location. These operating segments are evaluated for similarity with regards to economic characteristics, products, production processes, types or classes of customers, distribution methods and regulatory environments to determine if they can be aggregated into reportable segments.  Beginning in the fourth quarter of 2011, the Company has the following reportable segments: U.S. Morning Foods and Kashi; U.S. Snacks; U.S. Specialty; North America Other; Europe; Latin America; and Asia Pacific.  In addition, subsequent to the filing of the Company’s Annual Report on Form 10-K, the Company reclassified certain customers between reportable segments within North America. Segment results of prior periods were recast to conform to the current presentation.  The reportable segments are discussed in greater detail below.
U.S. Morning Foods and Kashi [Member]
Segment Reporting Information [Line Items]
Net sales	946	897	2,826	2,782
Operating profit	137	134	479	491
Reportable segments information			U.S. Morning Foods and Kashi aggregates the U.S. Morning Foods and U.S. Kashi operating segments.  The U.S. Morning Foods operating segment includes cereal, toaster pastries, and health and wellness products generally marketed under the Kellogg’s name.  The U.S. Kashi operating segment represents Kashi-branded cereal, cereal bars, crackers, cookies and Stretch Island fruit snacks.
U.S. Snacks [Member]
Segment Reporting Information [Line Items]
Net sales	865	727	2,410	2,181
Operating profit	116	94	351	329
Reportable segments information			U.S. Snacks represents the U.S. snacks business which includes products such as cookies, crackers, cereal bars, savory snacks and fruit-flavored snacks.
U.S. Specialty [Member]
Segment Reporting Information [Line Items]
Net sales	264	234	864	789
Operating profit	62	64	188	185
Reportable segments information			U.S. Specialty primarily represents the food service, convenience and Girl Scouts businesses. The food service business is mostly non-commercial, servicing institutions such as schools and hospitals.
North America Other [Member]
Segment Reporting Information [Line Items]
Net sales	388	359	1,125	1,060
Operating profit	66	65	206	198
Reportable segments information			North America Other represents the U.S. Frozen and Canada operating segments.  As these operating segments are not considered economically similar enough to aggregate with other operating segments and are immaterial for separate disclosure, they have been grouped together as a single reportable segment.
Europe [Member]
Segment Reporting Information [Line Items]
Net sales	685	585	1,836	1,840
Operating profit	84	84	234	287
Reportable segments information			Europe which consists principally of European countries;
Latin America [Member]
Segment Reporting Information [Line Items]
Net sales	292	274	836	816
Operating profit	35	43	134	152
Reportable segments information			Latin America which is comprised of Central and South America and includes Mexico;
Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net sales	280	236	737	715
Operating profit	29	23	79	79
Reportable segments information			Asia Pacific which is comprised of South Africa, Australia and other Asian and Pacific markets.
Total Reportable Segments [Member]
Segment Reporting Information [Line Items]
Operating profit	529	507	1,671	1,721
Corporate [Member]
Segment Reporting Information [Line Items]
Operating profit	$ (50)	$ (43)	$ (172)	$ (142)