Leases - Lease Cost and Other Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finance leases
Amortization of ROU assets	$ 10.9	$ 9.1
Interest on lease liabilities	1.8	2.1
Operating leases	31.1	32.9
Short-term lease cost	3.7	5.9
Variable lease cost	5.8	5.2
Total lease cost	53.3	55.2
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows - finance leases	4.4	5.1
Operating cash flows - operating leases	33.3	34.7
Financing cash flows - finance leases	11.6	9.3	$ 1.6
ROU assets obtained in exchange for new finance lease liabilities	7.1	21.3
ROU assets obtained in exchange for new operating lease liabilities	$ 14.3	$ 34.7
Finance leases
Remaining lease term (in years)	6 years 1 month 6 days	6 years 4 months 24 days
Discount rate	4.70%	4.90%
Operating leases
Remaining lease term (in years)	4 years 6 months	4 years 10 months 24 days
Discount rate	5.00%	5.20%