Leases - Summary of Future Lease Payments due from Company Under Ground, Office and Equipment Operating Leases (ASC 842) (Details) $ in Thousands	Mar. 31, 2019 USD ($)
Lessee Lease Description [Line Items]
April 1 - December 31, 2019	$ 1,023
2020	1,087
2021	1,011
2022	996
2023	682
Thereafter	1,094
Total	5,893
Present value discount	(1,276)
Lease liability	4,617
Office and Ground Leases to be Paid by the Company
Lessee Lease Description [Line Items]
April 1 - December 31, 2019	653
2020	759
2021	680
2022	669
2023	656
Thereafter	1,094
Total	4,511
Ground Leases to be Paid Directly by the Company's Tenants
Lessee Lease Description [Line Items]
April 1 - December 31, 2019	370
2020	328
2021	331
2022	327
2023	26
Total	$ 1,382