Face (par) amount of debt instrument at time of issuance.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The estimated value of gains (losses), net anticipated to be transferred in the future from accumulated other comprehensive income into earnings.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=121549185&loc=d3e80845-113994

+ Details

Name:	us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CurrencySwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_CashFlowHedgingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=man_NotesDueSeptember2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=man_NotesDueJune2026Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=man_EurodenominatedNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Derivative Financial Instruments - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2020 EUR (€)	Sep. 30, 2019 EUR (€)	Apr. 30, 2019 EUR (€)	Jun. 22, 2018 EUR (€)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Pre-tax derivative gains and losses included in AOCI to be reclassified into earnings over the next twelve months \| $	$ 1.0
Cross-currency swap \| Cash flow hedge
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt			€ 55,400,000	€ 202,300,000
Fixed annual interest rate			1.143%	1.256%
Notes due September 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt		€ 400,000,000.0
Fixed annual interest rate	1.875%	1.875%
Notes Due June 2026
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt		€ 500,000,000.0			€ 500,000,000.0
Fixed annual interest rate					1.75%
Designated as hedging instrument \| Notes due September 2022 \| Euro-denominated notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 487.8	400,000,000.0
Designated as hedging instrument \| Notes Due June 2026 \| Euro-denominated notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 606.7	€ 500,000,000.0