Leases - Lease Cost and Other Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Finance Leases [Abstract]
Amortization of ROU assets	$ 2.7	$ 2.6	$ 7.9	$ 8.1
Interest on lease liabilities	0.3	0.5	1.1	1.4
Operating leases	7.7	7.1	23.0	23.0
Short-term lease cost	1.3	1.0	3.8	2.7
Variable lease cost	1.8	1.3	4.5	4.1
Total lease cost	$ 13.8	$ 12.5	40.3	39.3
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows - finance leases			3.6	3.3
Operating cash flows - operating leases			22.5	23.9
Financing cash flows - finance leases			7.8	8.7
Right-Of-Use Asset Obtained In Exchange For Lease Liability [Abstract]
ROU assets obtained in exchange for new finance lease liabilities			4.7	5.3
ROU assets obtained in exchange for new operating lease liabilities			$ 14.0	$ 9.6
Finance leases
Remaining lease term (in years)	5 years 10 months 24 days	6 years 1 month 6 days	5 years 10 months 24 days	6 years 1 month 6 days
Discount rate	4.60%	4.80%	4.60%	4.80%
Operating leases
Remaining lease term (in years)	4 years 4 months 24 days	4 years 8 months 12 days	4 years 4 months 24 days	4 years 8 months 12 days
Discount rate	4.70%	5.10%	4.70%	5.10%