Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefit that Would Not Impact Effective Tax Rate, Tax Position with Uncertain Timing of Deductibility	$ 7.6	$ 7.6
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	0.5	$ 0.5
Proceeds from Income Tax Refunds	$ 4.6