Leases - Narrative (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) office_lease ground_lease	Mar. 31, 2018 USD ($)
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 | $	$ 1,540	$ 2,041
Number of ground leases | ground_lease	8
Number of office leases | office_lease	1
Weighted-average remaining term of operating leases	38 years 9 months 18 days
Weighted-average discount rate of operating leases (as a percent)	8.10%
Minimum
Lessee, Lease, Description [Line Items]
Operating lease renewal term	5 years
Maximum
Lessee, Lease, Description [Line Items]
Operating lease renewal term	10 years