Goodwill and Other Intangible Assets - Goodwill Rollforward (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 25.9	$ 25.9
Intangible assets, net (including Goodwill), beginning balance	62.1	45.2
Amortization, including foreign currency translation	(2.9)	(2.3)
Goodwill, ending balance	25.9	25.9
Intangible assets, net (including Goodwill), ending balance	59.2	42.9
Other Intangible Assets
Goodwill [Roll Forward]
Other intangible assets, beginning balance	36.2	19.3
Amortization, including foreign currency translation	(2.9)	(2.3)
Other intangible assets, ending balance	$ 33.3	$ 17.0