Leases - Lease Cost and Other Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Finance Leases [Abstract]
Amortization of ROU assets	$ 2.6	$ 2.4	$ 8.1	$ 6.5
Interest on lease liabilities	0.5	0.5	1.4	1.5
Operating leases	7.1	7.4	23.0	23.7
Short-term lease cost	1.0	2.0	2.7	3.9
Variable lease cost	1.3	1.6	4.1	4.7
Total lease cost	$ 12.5	$ 13.9	39.3	40.3
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows - finance leases			3.3	3.9
Operating cash flows - operating leases			23.9	26.1
Financing cash flows - finance leases			8.7	6.5
Right-Of-Use Asset Obtained In Exchange For Lease Liability [Abstract]
ROU assets obtained in exchange for new finance lease liabilities			5.3	19.6
ROU assets obtained in exchange for new operating lease liabilities			$ 9.6	$ 14.5
Finance leases
Remaining lease term (in years)	6 years 1 month 6 days	6 years 4 months 24 days	6 years 1 month 6 days	6 years 4 months 24 days
Discount rate	4.80%	5.00%	4.80%	5.00%
Operating leases
Remaining lease term (in years)	4 years 8 months 12 days	4 years 10 months 24 days	4 years 8 months 12 days	4 years 10 months 24 days
Discount rate	5.10%	5.40%	5.10%	5.40%