Leases - Components of Lease Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Leases [Abstract]
Finance lease income	$ 1.8	$ 2.8
Operating lease income:
Variable lease income	255.1	253.9
Operating Lease, Variable Lease Income	14.8	17.7
Operating Lease, Lease Income	269.9	271.6
Total operating lease income	22.7	23.7
Total lease income	$ 271.7	$ 274.4