Leases ASC 842 (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) propertyUnit	Dec. 31, 2019 USD ($)
Lessor Disclosure [Abstract]
Rental and other revenues related to operating lease payments	$ 726,000	$ 723,100
Variable lease payments	56,000	65,400
Operating leases, scheduled future minimum payments receivable [Abstract]
2021	623,888
2022	619,530
2023	570,417
2024	513,483
2025	432,272
Thereafter	2,049,545
Operating leases, total future minimum payments receivable due	$ 4,809,135
Lessee Disclosure [Abstract]
Number of properties subject to ground leases | propertyUnit	20
Weighted average remaining term of ground leases (in years)	51 years
Operating lease liability upon initial adoption	$ 35,300
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent
Right of use asset upon initial adoption	$ 29,700
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:PrepaidExpenseAndOtherAssets
Operating lease discount rate (in hundredths)	4.50%
Operating ground lease expense	$ 2,600	2,500
Operating ground lease payments	2,200	$ 2,200
Operating ground lease liabilities, scheduled future minimum payments [Abstract]
2021	2,127
2022	2,169
2023	2,167
2024	2,123
2025	2,170
Thereafter	81,527
Operating ground lease liability, total future minimum payments	92,283
Operating lease liability discount	(57,892)
Operating lease liability	$ 34,391
Minimum [Member]
Lessor Disclosure [Abstract]
Operating leases, term of leases	3 years
Maximum [Member]
Lessor Disclosure [Abstract]
Operating leases, term of leases	10 years