Income Taxes Income Taxes - Rollforward of Deferred Tax Assets Valuation Allowance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Valuation Allowance [Line Items]
Deferred Tax Assets, Valuation Allowance, Beginning Balance	$ 170.0	$ 113.3	$ 135.7
Deferred Tax Asset Valuation Allowance, Change in Assessment	(22.9)	0.0	(0.3)
Deferred Tax Asset Valuation Allowance, Current Year Operations	(6.1)	56.7	(22.1)
Deferred Tax Assets, Valuation Allowance, Ending Balance	141.0	170.0	113.3
Domestic Tax Authority [Member]
Valuation Allowance [Line Items]
Deferred Tax Assets, Valuation Allowance, Beginning Balance	0.0	0.0	0.0
Deferred Tax Asset Valuation Allowance, Change in Assessment	0.0	0.0	0.0
Deferred Tax Asset Valuation Allowance, Current Year Operations	0.0	0.0	0.0
Deferred Tax Assets, Valuation Allowance, Ending Balance	0.0	0.0	0.0
State and Local Jurisdiction [Member]
Valuation Allowance [Line Items]
Deferred Tax Assets, Valuation Allowance, Beginning Balance	72.4	45.9	41.5
Deferred Tax Asset Valuation Allowance, Change in Assessment	0.0	0.0	0.0
Deferred Tax Asset Valuation Allowance, Current Year Operations	(15.1)	26.5	4.4
Deferred Tax Assets, Valuation Allowance, Ending Balance	57.3	72.4	45.9
Foreign Tax Authority [Member]
Valuation Allowance [Line Items]
Deferred Tax Assets, Valuation Allowance, Beginning Balance	97.6	67.4	94.2
Deferred Tax Asset Valuation Allowance, Change in Assessment	(22.9)	0.0	(0.3)
Deferred Tax Asset Valuation Allowance, Current Year Operations	9.0	30.2	(26.5)
Deferred Tax Assets, Valuation Allowance, Ending Balance	$ 83.7	$ 97.6	$ 67.4