Leases - Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease cost	$ 33.1	$ 32.6
Variable lease cost	7.2	2.2
Cash paid for amounts included in measurement of operating lease liabilities - operating cash flows	26.5	24.3
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 10.0	$ 21.0