Goodwill and Other Intangible Assets - Goodwill Rollforward (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 187.9	$ 169.2	$ 187.9	$ 168.9
Intangible Assets, Net (Excluding Goodwill)	183.6	178.2	$ 187.8	$ 182.3
Goodwill, Acquired During Period	0.0	0.3
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	3.9	2.8
Amortization of Intangible Assets	$ (8.1)	$ (6.9)