Goodwill and Intangibles - Schedule of Finite-Lived Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Finite-lived Intangible Assets Acquired	$ 15.7	$ 0.0	$ 15.7	$ 48.0
Finite-Lived Intangible Assets, Period Increase (Decrease)	0.0	0.0	0.0	(3.1)
Goodwill [Roll Forward]
CDI, net, beginning of period	45.6	52.8	49.1	9.6
CDI current period amortization	(2.0)	(1.9)	(5.5)	(3.6)
Total CDI, net, at September 30	$ 59.3	$ 50.9	$ 59.3	$ 50.9