Income Taxes - Narrative (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefit that Would Not Impact Effective Tax Rate, Tax Position with Uncertain Timing of Deductibility	$ 8.6		$ 7.6
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	0.6		$ 0.5
Income Taxes Paid, Net	$ 0.4	$ 3.0