Goodwill and Intangible Assets, Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 18.8		$ 18.8		$ 37.2	$ 37.2
Goodwill impairment	$ 0.0	$ 0.0	$ 18.4	$ 0.0
Impairment of Intangible Assets, Finite-lived		$ 2.6