Income Taxes - Income Tax Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax [Line Items]
Income tax based on statutory rate		$ 143.9	$ 158.5	$ 258.1
Increase (decrease) resulting from:
Repatriation of non-United States earnings		(17.8)	2.5	69.7
State income taxes, net of federal benefit		3.1	8.2	1.1
Change in valuation allowance		20.0	0.7	(6.9)
Work Opportunity Tax Credit		(10.4)	(8.8)	(10.5)
Foreign-Derived Intangible Income deduction		(11.9)	(12.5)
United States Tax Act and French tax reform	$ (73.7)		3.2	(73.7)
Goodwill impairment		11.9
Other, net		11.6	7.0	12.9
Total provision		219.8	198.0	191.9
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:		54.9	59.1	46.9
French CICE
Increase (decrease) resulting from:
Non-United States tax rate difference:			(39.9)	(77.1)
Other
Increase (decrease) resulting from:
Non-United States tax rate difference:		$ 37.3	$ 20.0	$ (28.6)

Income tax.

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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 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 deductions. Including, but not limited to, extraterritorial income exclusion deduction, qualified production activity deduction, dividend deduction, deduction for dividend paid to employee stock ownership plan, Medicare prescription drug benefit subsidy deduction, and other deductions.

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