Other Comprehensive Income (Loss) - Changes in AOCI (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance, Stockholders' Equity	[1]	$ 494.0	$ 461.3	$ 434.0
Ending Balance, Stockholders' Equity	[1]	529.8	494.0	461.3
Defined Benefit Plan
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance, Stockholders' Equity		(10.6)	(10.8)	(7.9)
Other comprehensive loss		0.2	0.2	(2.9)
Ending Balance, Stockholders' Equity		(10.4)	(10.6)	(10.8)
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance, Stockholders' Equity		(5.7)	(0.8)	2.2
Other comprehensive loss		1.9	(4.9)	(3.0)
Ending Balance, Stockholders' Equity		(3.8)	(5.7)	(0.8)
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance, Stockholders' Equity	[1]	(16.3)	(11.6)	(5.7)
Other comprehensive loss		2.1	(4.7)	(5.9)
Ending Balance, Stockholders' Equity	[1]	$ (14.2)	$ (16.3)	$ (11.6)

[1] Amounts have been rounded for presentation purposes and might differ from unrounded results.