Income Taxes - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Effective income tax rate (percent)	38.40%	37.80%
Gross unrecognized tax benefit	$ 3.8		$ 3.4
Expected change in unrecognized tax benefits	1.2
Accrued interest on income taxes	4.7		3.9
Accrued penalties on income taxes	$ 0.1		$ 0.1