Derivative Instruments and Fair Value Accounting FX Hedge (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Foreign Currency Fair Value Hedge Derivative [Line Items]
Total stockholders' equity		$ 1,967.9	$ 2,466.1	$ 2,016.0	$ 2,378.9
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member]
Foreign Currency Fair Value Hedge Derivative [Line Items]
Derivative, Notional Amount		40.0
Derivative Asset		1.6
Foreign Exchange Contract [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Designated as Hedging Instrument [Member]
Foreign Currency Fair Value Hedge Derivative [Line Items]
Total stockholders' equity		(3.1)
Foreign Exchange Contract [Member] | Interest Expense [Member] | Designated as Hedging Instrument [Member]
Foreign Currency Fair Value Hedge Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		(3.7)	$ (0.8)
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	[1]	$ (3.1)

[1] (Mark One)