Income Taxes Income Taxes - Rollforward of Deferred Tax Assets Valuation Allowance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Valuation Allowance [Line Items]
Deferred Tax Assets, Valuation Allowance, Beginning Balance	$ 129.8	$ 141.0	$ 170.0
Change in assessment	(6.2)	5.6	(22.9)
Current year operations	(0.6)	(16.8)	(6.1)
Deferred Tax Assets, Valuation Allowance, Ending Balance	123.0	129.8	141.0
State and Local Jurisdiction [Member]
Valuation Allowance [Line Items]
Deferred Tax Assets, Valuation Allowance, Beginning Balance	48.5	57.3	72.4
Change in assessment	0.0	0.0	0.0
Current year operations	(8.1)	(8.8)	(15.1)
Deferred Tax Assets, Valuation Allowance, Ending Balance	40.4	48.5	57.3
Foreign Tax Authority [Member]
Valuation Allowance [Line Items]
Deferred Tax Assets, Valuation Allowance, Beginning Balance	81.3	83.7	97.6
Change in assessment	(6.2)	5.6	(22.9)
Current year operations	7.5	(8.0)	9.0
Deferred Tax Assets, Valuation Allowance, Ending Balance	$ 82.6	$ 81.3	$ 83.7