Business Combination, Indemnification Liabilities, Amount as of Acquisition Date

No definition available.

Name:	kelya_BusinessCombinationIndemnificationLiabilitiesAmountAsOfAcquisitionDate
Namespace Prefix:	kelya_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Business Combination, Indemnification Liabilities, Range of Outcomes, Value, High

+ References

No definition available.

+ Details

Name:	kelya_BusinessCombinationIndemnificationLiabilitiesRangeOfOutcomesValueHigh
Namespace Prefix:	kelya_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of consideration received or receivable for the disposal of assets and liabilities, including discontinued operation.

+ References

No definition available.

+ Details

Name:	us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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

- Definition

This element represents the cash inflow during the period from the sale of a component of the entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3179-108585

+ Details

Name:	us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=kelya_BrazilOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Acquisitions and Disposition - Disposition Narrative (Details) - USD ($) $ in Millions		9 Months Ended
	Aug. 18, 2020	Sep. 27, 2020	Sep. 29, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of Brazil, net of cash disposed		$ 1.2	$ 0.0
Brazil
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Purchase price of disposition	$ 1.4
Proceeds from sale of Brazil, net of cash disposed	1.2
Indemnification liabilities, range of outcomes, value, high	8.8
Indemnification liability	$ 2.5