Income Taxes - Tax Reform (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income tax benefit			$ 9.9
Provisional impact related to remeasuring deferred taxes			51.3
Offsetting tax benefit of remeasured valuation allowance			51.3
Transition tax reserve recorded	$ 20.3		$ 20.3
Provisional reduction to NOLs	$ 102.6
Additional valuation allowance recorded		$ 20.3
GILTI taxable income included in income tax provision		$ 33.6