Investments in Real Estate - Summary of Acquired Wholly Owned Industrial Properties (Detail) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
	Apr. 28, 2017 USD ($)	Jun. 30, 2017 USD ($) ft² $ / shares	Jun. 30, 2016 USD ($) $ / shares	Jun. 30, 2017 USD ($) ft² building $ / shares	Jun. 30, 2016 USD ($) $ / shares
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Revenue		$ 39,222	$ 34,134	$ 78,324	$ 65,170
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual		$ 1,391		$ 1,391
Rentable Square Feet | ft²		1,764,112		1,764,112
Number of Buildings | building				23
Purchase Price				$ 241,309
Capitalized acquisition costs		$ 600
Payments to acquire real estate				240,447	228,131
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual		(262)		(280)
Business Acquisition, Pro Forma Net Income (Loss)		$ 18,664	$ 11,541	$ 22,748	$ 12,195
Business Acquisition, Pro Forma Earnings Per Share, Basic | $ / shares		$ 0.27	$ 0.18	$ 0.34	$ 0.19
Business Acquisition, Pro Forma Earnings Per Share, Diluted | $ / shares		$ 0.27	$ 0.18	$ 0.34	$ 0.19
Below Market Lease, Weighted Average Useful Life				3 years 1 month 29 days
28903 Avenue Paine
Business Acquisition [Line Items]
Date of Acquisition				Feb. 17, 2017
Rentable Square Feet | ft²		111,346		111,346
Number of Buildings | building				1
Purchase Price				$ 17,060
2390 Ward Avenue
Business Acquisition [Line Items]
Date of Acquisition				Apr. 28, 2017
Rentable Square Feet | ft²		138,700		138,700
Number of Buildings | building				1
Purchase Price				$ 16,499
Safari Business Center
Business Acquisition [Line Items]
Date of Acquisition				May 24, 2017
Rentable Square Feet | ft²		1,138,090		1,138,090
Number of Buildings | building				16
Purchase Price				$ 141,200
4175 Conant Street
Business Acquisition [Line Items]
Date of Acquisition				Jun. 14, 2017
Rentable Square Feet | ft²		142,593		142,593
Number of Buildings | building				1
Purchase Price				$ 30,600
5421 Argosy Avenue
Business Acquisition [Line Items]
Date of Acquisition				Jun. 15, 2017
Rentable Square Feet | ft²		35,321		35,321
Number of Buildings | building				1
Purchase Price				$ 5,300
14820-14830 Carmenita Road
Business Acquisition [Line Items]
Date of Acquisition				Jun. 30, 2017
Rentable Square Feet | ft²		198,062		198,062
Number of Buildings | building				3
Purchase Price				$ 30,650
2535 Midway Drive
Business Acquisition [Line Items]
Payments to acquire real estate				$ 39,700
Archibald Ave
Business Acquisition [Line Items]
Payments to acquire real estate	$ 6,500
In-place lease intangibles
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life				5 years 1 month 7 days
Above Market Leases
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life				11 years 2 months 30 days