Nature of Business and Accounting Policies - Foreign Currency Gain (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Foreign Currency Translation
Net unrealized losses related to foreign currency translation	$ (2.1)	$ (1.0)	$ (0.3)
Net foreign currency transaction gain (loss)	$ (6.8)	$ (6.4)	$ 5.1