Summary of Significant Accounting Policies - Deferred Costs and Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Deferred costs and intangible assets, net:
In-place lease value, net	$ 5,086	$ 6,437
Goodwill	21,387	21,387
Other intangible assets	380	380
Subtotal intangible assets	26,853	28,204
Deferred costs, net	98	151
Total	$ 26,951	$ 28,355
Terminal capitalization rate | Discounted cash flow method | Minimum
Property, Plant and Equipment [Line Items]
Goodwill impairment measurement input	6.50%
Terminal capitalization rate | Discounted cash flow method | Maximum
Property, Plant and Equipment [Line Items]
Goodwill impairment measurement input	7.75%
Discount rate | Discounted cash flow method | Minimum
Property, Plant and Equipment [Line Items]
Goodwill impairment measurement input	7.75%
Discount rate | Discounted cash flow method | Maximum
Property, Plant and Equipment [Line Items]
Goodwill impairment measurement input	9.25%