Annual cash payments associated with multi-employer pension plan withdrawal obligation.

No definition available.

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Namespace Prefix:	k_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Costs associated with exiting Multiemployer plans.

+ References

No definition available.

+ Details

Name:	k_MultiemployerPlanWithdrawalExpense
Namespace Prefix:	k_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Multiemployer plan withdrawal obligation term.

+ References

No definition available.

+ Details

Name:	k_MultiemployerPlanWithdrawalObligationTerm
Namespace Prefix:	k_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Cash payments for Multiemployer withdrawal obligations.

+ References

No definition available.

+ Details

Name:	k_MultiemployerWithdrawalLiabilityPayments
Namespace Prefix:	k_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage of employer contribution required by collective-bargaining arrangement (CBA) to total contribution from all participating employers in multiemployer pension plan determined to be individually insignificant.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 5
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947

+ Details

Name:	us-gaap_MultiemployerPlanPensionInsignificantEmployerContributionUnderCollectiveBargainingArrangementToAllParticipatingEmployerContributionsPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_MultiemployerPlansLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the obligation recognized by withdrawing from a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

+ References

No definition available.

+ Details

Name:	us-gaap_MultiemployerPlansWithdrawalObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_RestructuringPlanAxis=k_ProjectKMember
Namespace Prefix:
Data Type:	na
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Period Type:

Multipemployer Pension and Postretirement Plans Multiemployer Pension Plans Trusts Funds Contributions (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Jan. 02, 2021	Jun. 27, 2020	Jan. 02, 2021	Dec. 28, 2019	Dec. 29, 2018
Multiemployer Plans [Line Items]
Multiemployer plan withdrawal expense		$ 5
Multiemployer withdrawal obligation annual cash obligation			$ 8
Multiemployer Plans, Withdrawal Obligation	$ 130		$ 130	$ 156
Multiemployer plan withdrawal obligation term			20 years
Multiemployer withdrawal liability payments	$ 5	$ 7	$ 21	8	$ 3
Multiemployer Plan, Pension, Insignificant, Employer Contribution under Collective-Bargaining Arrangement to All Participating Employer Contributions, Percentage			5.00%
Project K
Multiemployer Plans [Line Items]
Multiemployer plan withdrawal expense			$ (5)	$ 132	$ 7