Goodwill and Other Intangible Assets - Goodwill Rollforward (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 31.7	$ 24.1	$ 31.7	$ 24.1
Intangible Assets, Net (Excluding Goodwill)	21.3	32.2	24.2	31.3
Goodwill and other intangible assets	53.0	56.3	55.9	55.4
Acquisition of businesses	0.0	3.9
Disposal Group, Including Discontinued Operation, Intangible Assets	0.0	0.3	0.0	0.4
Amortization of Intangible Assets	(2.9)	(3.1)
Intangible Asset and Goodwill [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Acquisition of businesses		3.9
Disposal Group, Including Discontinued Operation, Intangible Assets	0.0	0.3	$ 0.0	$ 0.4
Amortization of Intangible Assets	$ (2.9)	$ (3.1)