Leases ASC 842 (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Lessor Disclosure [Abstract]
Rental and other revenues related to operating lease payments	$ 192.3	$ 178.9	$ 554.6	$ 549.5
Variable lease income	13.7	$ 12.8	42.7	$ 42.7
Lessee Disclosure [Abstract]
Finance Lease, Liability	$ 5.3		$ 5.3
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Accounts Payable and Accrued Liabilities		Accounts Payable and Accrued Liabilities
Finance lease, right of use asset	$ 5.3		$ 5.3
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Prepaid expenses and other assets, net of accumulated depreciation of $20,891 and $21,154, respectively		Prepaid expenses and other assets, net of accumulated depreciation of $20,891 and $21,154, respectively
Finance lease discount rate (in hundredths)	2.60%		2.60%
Additional right of use asset	$ 3.1		$ 3.1
Minimum [Member]
Lessor Disclosure [Abstract]
Operating leases, term of leases (in years)	3 years		3 years
Maximum [Member]
Lessor Disclosure [Abstract]
Operating leases, term of leases (in years)	10 years		10 years