Leases - Narrative (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($) office_lease ground_lease	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) office_lease ground_lease	Jun. 30, 2018 USD ($)
Lessee, Lease, Description [Line Items]
Tenant reimbursements period related to certain capital expenditure minimum			5 years
Tenant reimbursements period related to certain capital expenditure maximum			15 years
Uncollectable operating lease receivables | $	$ 152	$ 745	$ 1,692	$ 2,786
Number of ground leases | ground_lease	8		8
Number of office leases | office_lease	1		1
Weighted-average remaining term of operating leases	39 years 3 months 18 days		39 years 3 months 18 days
Weighted-average discount rate of operating leases (as a percent)	8.00%		8.00%
Minimum
Lessee, Lease, Description [Line Items]
Operating lease renewal term	5 years		5 years
Maximum
Lessee, Lease, Description [Line Items]
Operating lease renewal term	10 years		10 years