Leases - Components of Lease Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Leases [Abstract]
Sublease Income	$ 17.2		$ 53.0
Finance lease income	2.2		7.7
Operating lease income:
Variable lease income	254.4		762.2
Operating Lease, Variable Lease Income	14.9		50.0
Operating Lease, Lease Income	269.3		812.2
Total operating lease income	22.3		66.6
Total lease income	$ 271.5	$ 271.9	$ 819.9	$ 816.1