Document and Entity Information Document - USD ($) $ in Billions	12 Months Ended
	Dec. 30, 2017	Jan. 27, 2018	Jul. 01, 2017
Entity Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 30, 2017
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2017
Trading Symbol	K
Entity Registrant Name	KELLOGG CO
Entity Central Index Key	0000055067
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-30
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Entity Common Stock, Shares Outstanding		345,748,749
Entity Public Float			$ 18.9