Leases ASC 842 (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) property
Lessor Disclosure [Abstract]
Rental and other revenues related to operating lease payments	$ 169,400
Variable lease income	15,500
Operating leases, scheduled future minimum payments receivable [Abstract]
Operating leases, scheduled future minimum payments receivable, remainder of 2019	466,042
Operating leases, scheduled future minimum payments receivable, 2020	586,386
Operating leases, scheduled future minimum payments receivable, 2021	530,336
Operating leases, scheduled future minimum payments receivable, 2022	494,060
Operating leases, scheduled future minimum payments receivable, 2023	433,593
Operating leases, scheduled future minimum payments receivable, 2024	372,614
Operating leases, scheduled future minimum payments receivable, thereafter	1,679,410
Operating leases, total future minimum payments receivable due	$ 4,562,441
Lessee Disclosure [Abstract]
Number of properties subject to ground leases | property	20
Weighted average remaining term of ground leases (in years)	52 years
Operating lease liability upon initial adoption	$ 35,300
Right of use asset upon initial adoption	$ 29,700
Operating lease discount rate (in hundredths)	4.50%
Operating ground lease expense	$ 600
Operating ground lease payments	500
Operating ground lease liabilities, scheduled future minimum payments [Abstract]
Operating ground lease liability, future minimum payments, remainder of 2019	1,539
Operating ground lease liability, future minimum payments, 2020	2,086
Operating ground lease liability, future minimum payments, 2021	2,127
Operating ground lease liability, future minimum payments, 2022	2,169
Operating ground lease liability, future minimum payments, 2023	2,167
Operating ground lease liability, future minimum payments, 2024	2,123
Operating ground lease liability, future minimum payments, thereafter	83,697
Operating ground lease liability, total future minimum payments	95,908
Operating lease liability discount	(60,668)
Operating lease liability	$ 35,240
Minimum [Member]
Lessor Disclosure [Abstract]
Operating leases, term of leases	3 years
Maximum [Member]
Lessor Disclosure [Abstract]
Operating leases, term of leases	10 years