Sale of Accounts Receivable (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Jul. 31, 2016
Receivables Sales Agreement
Transfer of Financial Assets Accounted for as Sales [Line Items]
Transfer of Accounts Receivable Agreements	$ 2,200	$ 1,500
Receivables Sales Agreement | Other Income (Expense), Net
Transfer of Financial Assets Accounted for as Sales [Line Items]
Gain (Loss) on Sale of Accounts Receivable	(11)	(5)
Receivables Sales Agreement | Maximum
Transfer of Financial Assets Accounted for as Sales [Line Items]
Transfers Of Accounts Receivable Agreements	800
Receivables Sales Agreement | Sold And Outstanding
Transfer of Financial Assets Accounted for as Sales [Line Items]
Transfer of Accounts Receivable Agreements	601	562
Kellogg Funding Company Program
Transfer of Financial Assets Accounted for as Sales [Line Items]
Transfer of Accounts Receivable Agreements	2,600	839
Cash Proceeds Received for Assets Derecognized	412	255
Gain (Loss) on Sale of Accounts Receivable	(7)
Deferred Purchase Price	21	37
Kellogg Funding Company Program | Maximum
Transfer of Financial Assets Accounted for as Sales [Line Items]
Transfers Of Accounts Receivable Agreements			$ 600
Kellogg Funding Company Program | Sold And Outstanding
Transfer of Financial Assets Accounted for as Sales [Line Items]
Transfer of Accounts Receivable Agreements	433	292
Kellogg Foreign Subsidiaries Other Program
Transfer of Financial Assets Accounted for as Sales [Line Items]
Transfer of Accounts Receivable Agreements	237	164
Kellogg Foreign Subsidiaries Other Program | Sold And Outstanding
Transfer of Financial Assets Accounted for as Sales [Line Items]
Transfer of Accounts Receivable Agreements	$ 86	$ 124