Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 01, 2022	Oct. 02, 2021	Oct. 01, 2022	Oct. 02, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 312	$ 305	$ 1,062	$ 1,061
Other comprehensive income (loss), pre-tax:
Foreign currency translation adjustments, pre-tax	(249)	(103)	(509)	(150)
Net investment hedges, pre-tax
Net investment hedge gain (loss), pre-tax	260	87	616	175
Cash flow hedges, pre-tax:
Unrealized gain (loss) on cash flow hedges, pre-tax	62	3	213	42
Reclassification to net income, pre-tax	(14)	4	(6)	19
Postretirement and postemployment benefits reclassification to net income, pre-tax:
Net experience (gain) loss	0	0	(2)	(2)
Available-for-sale securities, pre-tax
Unrealized gain (loss) on available-for-sale securities, pre-tax	(2)	0	(6)	(1)
Reclassification to net income on available-for-sale securities, pre-tax	1	(2)	1	(2)
Other comprehensive income (loss), pre-tax	58	(11)	307	81
Other comprehensive income (loss), tax (expense) benefit
Foreign currency translation adjustments, tax (expense) benefit	4	2	6	2
Net investment hedges, tax (expense) benefit
Net investment hedge gain (loss), tax (expense) benefit	(68)	(23)	(162)	(46)
Cash flow hedges, tax (expense) benefit:
Unrealized gain (loss) on cash flow hedges, tax (expense) benefit	(16)	(1)	(56)	(11)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, Tax	3	(1)	1	(5)
Postretirement and postemployment benefits reclassification to net income, tax (expense) benefit:
Net experience loss, tax (expense) benefit	0	0	1	1
Available-for-sale securities, tax (expense) benefit
Unrealized gain (loss) on available-for-sale securities, tax (expense) benefit	0	0	0	0
Reclassification to net income on available for sale of securities, tax (expense) benefit	0	0	0	0
Other comprehensive income (loss), tax (expense) benefit	(77)	(23)	(210)	(59)
Other comprehensive income (loss), after tax:
Foreign currency translation adjustments, after-tax	(245)	(101)	(503)	(148)
Net investment hedges, after tax
Net investment hedge gain (loss), after-tax	192	64	454	129
Cash flow hedges, after tax
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax	46	2	157	31
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax	(11)	3	(5)	14
Postretirement and postemployment benefits reclassification to net income, after-tax:
Net experience (gain) loss, after-tax	0	0	(1)	(1)
Available-for-sale securities, after tax
Unrealized gain (loss) on available-for-sale securities, after-tax	(2)	0	(6)	(1)
Reclassification to net income on available for sale securities, after tax	1	(2)	1	(2)
Other comprehensive income (loss)	(19)	(34)	97	22
Comprehensive income	293	271	1,159	1,083
Net income attributable to noncontrolling interests	2	(2)	4	6
Other comprehensive income (loss) attributable to noncontrolling interests	(22)	(4)	(26)	(17)
Comprehensive income attributable to Kellogg Company	$ 313	$ 277	$ 1,181	$ 1,094