Significant Accounting Policies - Additional Information (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2016 USD ($) acquisition	Dec. 31, 2017 USD ($) business_segment shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($) shares	Oct. 01, 2016 USD ($)	Jan. 01, 2016 USD ($)
Accounting Policies [Line Items]
Business segments | business_segment		4
Straight-line rent adjustments		$ 1,200	$ 1,100	$ 1,900
Contingent rents included in revenue		400	400	500
Leasing incentive amortization		800	800	800
Interest capitalized		1,300	1,000	1,000
Indirect project costs		2,400	1,700	2,100
Capitalized preacquisition development costs	$ 1,079	1,352	1,079
Accounts receivable, net	15,052	15,691	15,052
Allowance for doubtful accounts	$ 400	500	400
Stock-based compensation expense		1,323	1,082	931
Capitalized stock-based compensation		$ 400	$ 300	$ 400
Percentage of taxable income for distributions to stockholders		90.00%
Dilutive shares outstanding (in shares) | shares		0	0	0
Number of acquisitions | acquisition	2
Accrued Straight-line Rental Revenue
Accounting Policies [Line Items]
Accounts receivable, net	$ 12,300	$ 12,800	$ 12,300
Accounting Standards Update 2017-01
Accounting Policies [Line Items]
Cost capitalized subsequent to acquisition					$ 700
Pro Forma | Accounting Standards Update 2017-01
Accounting Policies [Line Items]
Cost capitalized subsequent to acquisition						$ 1,400