Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Leases
Operating lease cost	$ 84.4	$ 82.7	$ 77.9
Operating lease cost from related parties	2.5	4.1	$ 3.4
Cash payments for operating leases	84.6
Right-of-use assets obtained in exchange for operating lease obligations	$ 71.1
Weighted average remaining lease term - operating leases	5 years 7 months 6 days
Weighted average discount rate - operating leases	4.30%
Maturities of operating lease liabilities
2020	$ 59.6
2021	47.8
2022	35.9
2023	27.5
2024	20.7
Thereafter	39.6
Total operating lease payments	231.1
Less: imputed interest	(29.1)
Total operating lease liabilities	$ 202.0
Maturities of non-cancellable operating leases under ASC 840.
2019		59.5
2020		45.5
2021		32.9
2022		22.7
2023		16.2
Thereafter		40.7
Total operating lease payments		$ 217.5