Summary of Significant Accounting Policies - Future Amortization of Intangibles (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Below Market Ground Leases & Other
Schedule of Finite-Lived Intangible Assets and Liabilities [Line Items]
2018, intangible assets	$ 2,558
2019, intangible assets	1,942
2020, intangible assets	1,591
2021, intangible assets	1,571
2022, intangible assets	1,534
Thereafter, intangible assets	9,718
Total future amortization, intangible assets	18,914
Above Market Ground Leases
Schedule of Finite-Lived Intangible Assets and Liabilities [Line Items]
2018, intangible liabilities	(455)
2019, intangible liabilities	(447)
2020, intangible liabilities	(443)
2021, intangible liabilities	(354)
2022, intangible liabilities	(18)
Thereafter, intangible liabilities	(24)
Total future amortization, intangible liabilities	$ (1,741)	$ (2,196)