Income Taxes - Income Tax Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax [Line Items]
Income tax based on statutory rate	$ 31.0	$ 143.9	$ 158.5
Increase (decrease) resulting from:
Repatriation of non-United States earnings	(2.0)	(17.8)	2.5
State income taxes, net of federal benefit	(1.3)	3.1	8.2
Change in valuation allowance	48.5	20.0	0.7
Work Opportunity Tax Credit	(4.9)	(10.4)	(8.8)
Foreign-Derived Intangible Income deduction	(8.8)	(11.9)	(12.5)
United States Tax Act and French tax reform			3.2
Goodwill impairment	13.4	11.9
Other, net	(5.4)	11.6	7.0
Total provision	123.9	219.8	198.0
Manpower Switzerland and Greater China
Increase (decrease) resulting from:
Gain related to Manpower Switzerland and Greater China transactions		(22.8)
French Business Tax
Increase (decrease) resulting from:
Non-United States tax rate difference:	43.7	54.9	59.1
French CICE
Increase (decrease) resulting from:
Non-United States tax rate difference:			(39.9)
Other
Increase (decrease) resulting from:
Non-United States tax rate difference:	$ 9.7	$ 37.3	$ 20.0

Income tax.

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Income tax reconciliation change in repatriation of foreign earnings.

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Amount of income tax expense (benefit) from effect of Tax Cuts and Jobs Act of 2017 and French tax reform.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operations attributable to deduction. Includes, but is not limited to, dividend deduction, deduction for dividend paid to employee stock ownership plan (ESOP), Medicare prescription drug benefit subsidy deduction, and other deductions.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to tax credits. Including, but not limited to, research credit, foreign tax credit, investment tax credit, and other tax credits.

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