Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Accounting Policies [Abstract]
Charge for uncollectible amounts	$ 29.8	$ 1.0	$ 35.0	$ 3.4
Office parking revenue	14.7	$ 26.9	44.9	$ 53.3
Office parking receivables	$ 0.4		$ 0.4		$ 1.3
Revenue type	us-gaap:ParkingMember	us-gaap:ParkingMember	us-gaap:ParkingMember	us-gaap:ParkingMember