Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Maturity of liquid investments	three months or less
Allowance for doubtful accounts receivable	$ 310	$ 528
Deferred rent receivable allowance amount	$ 1,557	1,694
Minimum percentage of taxable income to be distributed	90.00%
In-Place Leases and Tenant Relationships
Finite-Lived Intangible Assets [Line Items]
Amortization expense of deferred leasing intangibles	$ 6,648	6,717	$ 6,326
Above and Below Market Leases
Finite-Lived Intangible Assets [Line Items]
Amortization expense of deferred leasing intangibles	$ 1,116	$ 996	$ 462