Leases - Operating Lease Cost and Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Feb. 07, 2019	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease costs	$ 2.8	$ 27.5	$ 24.6
Variable lease costs	1.0	3.6	3.9
Short-term lease costs	0.0	0.4	0.2
Sublease income	(0.1)	(0.8)	(0.7)
Total lease costs	$ 3.7	$ 30.7	$ 28.0