Summary of Significant Accounting Policies - Summary of Deferred Leasing Intangibles (Phantoms) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Total accumulated amortization of deferred leasing intangibles included in total assets	$ 29,604	$ 27,336
Total accumulated amortization of deferred leasing intangibles included in total liabilities	$ 10,578	$ 10,193