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Income Taxes - Reconciliation of Income Tax Expense due to the U.S. Federal Statutory Corporate Tax Rate (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Provision at the U.S. federal statutory rate	$ 77.7	$ 47.7	$ 43.1
Increase (decrease) resulting from:
State income tax, net of benefit for federal deduction	5.8	5.2	3.6
Foreign income tax rate differential	(1.4)	0.9	(0.3)
Tax Credits	(0.3)	(1.1)	(1.3)
Changes in valuation allowances	2.3	(1.7)	3.4
Tax Act — Enactment date effect	0.0	0.0	(0.6)
Stock-based compensation	(0.8)	0.0	(0.1)
Uncertain tax benefits	(0.3)	0.7	0.4
Other	0.8	1.6	(0.7)
(Benefit) provision for income taxes	$ 83.8	$ 53.3	$ 47.6

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Increase Decrease Resulting From The Computation Of Income Tax By The Company And Statutory Body Abstract.

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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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