Comprehensive Income - Components of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
AOCI Attributable to Parent, Net of Tax [Roll Forward]
December 31, 2015			$ 250.1
Change in other comprehensive income (loss)	$ (0.2)	$ (0.1)	(0.3)	$ (0.6)
June 30, 2016	256.9		256.9
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
December 31, 2015			(1.2)
Change in other comprehensive income (loss)			0.0
June 30, 2016	(1.2)		(1.2)
Effective Portion of Unrealized Gain (Loss) on Cash Flow Hedge
AOCI Attributable to Parent, Net of Tax [Roll Forward]
December 31, 2015			0.1
Change in other comprehensive income (loss)			(0.3)
June 30, 2016	(0.2)		(0.2)
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
December 31, 2015			(1.1)
Change in other comprehensive income (loss)			(0.3)
June 30, 2016	$ (1.4)		$ (1.4)