Leases - Lease Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Finance lease costs
Amortization of lease right of use assets	$ 3.9	$ 3.7	$ 11.7	$ 10.2
Interest on lease liabilities	1.0	1.1	3.2	3.1
Operating lease costs	74.3	79.3	225.5	214.0
Short-term lease costs	15.5	23.1	44.0	71.7
Variable lease costs	8.8	6.6	23.0	25.4
Total lease costs	$ 103.5	$ 113.8	$ 307.4	$ 324.4