Leases - Components of Lease Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Leases [Abstract]
Sublease Income	$ 17.8		$ 35.8
Finance lease income	2.7		5.5
Operating lease income:
Variable lease income	253.9		507.8
Operating Lease, Variable Lease Income	17.4		35.1
Operating Lease, Lease Income	271.3		542.9
Total operating lease income	20.6		44.3
Total lease income	$ 274.0	$ 271.0	$ 548.4	$ 544.2