Leases - Components of Lease Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Operating lease income:
Variable lease income	$ 264.6	$ 258.6	$ 795.0	$ 764.7
Operating Lease, Variable Lease Income	17.4	13.2	51.9	43.7
Operating Lease, Lease Income	282.0	271.8	846.9	808.4
Finance lease income	1.9	1.5	5.2	4.9
Total lease income	283.9	273.3	852.1	813.3
Total operating lease income	$ 18.9	$ 22.7	$ 54.6	$ 69.1