Leases - Lease Cost (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Finance lease costs
Amortization of lease right of use assets	$ 3.9	$ 3.6	$ 7.8	$ 6.5
Interest on lease liabilities	1.1	1.1	2.2	2.0
Operating lease costs	76.1	74.2	151.2	134.7
Short-term lease costs	12.4	26.6	28.5	48.6
Variable lease costs	7.2	8.2	14.2	18.8
Total lease costs	$ 100.7	$ 113.7	$ 203.9	$ 210.6