Leases - Lease Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Operating lease costs	$ 19.3
Variable lease costs	4.5
Sublease income	(0.4)
Total lease costs	23.4	$ 20.6
Operating cash flows from operating leases (fixed payments)	17.5
Operating cash flows from operating leases (liability reduction)	$ 18.3