Leases (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Leases
Operating lease cost	$ 21.1	$ 20.8
Cash payments for operating leases	21.2	20.2
Right-of-use assets obtained in exchange for operating lease obligations	$ 14.5	$ 11.7
Weighted average remaining lease term - operating leases	5 years 6 months		5 years 7 months 6 days
Weighted average discount rate - operating leases	4.20%		4.30%
Maturities of operating lease liabilities
2020 (remaining nine months)	$ 45.1
2021	50.4
2022	39.0
2023	30.0
2024	23.1
Thereafter	41.9
Total operating lease payments	229.5
Less: imputed interest	(27.4)
Total operating lease liabilities	$ 202.1