Leases - Lease Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Components of lease cost
Amortization of right-of-use assets	$ 1.5	$ 0.7	$ 0.3
Interest on lease liabilities	0.1	0.1	0.0
Total finance lease cost	1.6	0.8	0.3
Operating lease cost	24.0	23.3	24.9
Short term lease cost	4.2	3.9	2.2
Variable lease cost	3.0	3.4	3.5
Sublease income	(2.0)	(1.9)	(1.2)
Total lease cost	$ 30.8	$ 29.5	$ 29.7