Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Effective tax rate (percent)	15.40%	32.30%
Unrecognized tax benefits	$ 11.8
Unrecognized tax benefits that would decrease the effective tax rate if recognized	10.3
Unrecognized tax benefits that could be recognized within 12 months	3.7
Unrecognized tax benefits, penalties accrued	$ 0.7