Leases - Lease Cost and Other Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Leases [Abstract]
Operating lease cost	$ 12.4	$ 12.1
Depreciation of finance lease assets	1.6	2.8
Interest on finance lease liabilities	0.2	0.4
Total lease cost	14.2	15.3
Operating cash outflows from operating leases	(13.6)	(12.5)
Operating cash outflows from finance leases	(0.2)	(0.4)
Financing cash outflows from finance leases	$ (1.9)	$ (2.1)
Weighted-average remaining lease term - operating leases	9 years 3 months 18 days	9 years 8 months 12 days
Weighted-average remaining lease term - finance leases	2 years 2 months 12 days	2 years 9 months 18 days
Weighted-average discount rate - operating leases	4.00%	3.90%
Weighted-average discount rate - finance leases	3.70%	4.40%