Income Taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Effective income tax rate reconciliation, at federal statutory income tax rate	35.00%	35.00%	35.00%
Current net income tax receivable	$ 5.7	$ 5.8
Benefit due to enactment of federal tax reform	$ 2.2	$ 0.0	$ 0.0