Investment in Real Estate - Additional Information (Detail) ft² in Thousands, $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2015 USD ($) ft² Land_Parcel Property	Jun. 30, 2014 USD ($) Property	Dec. 31, 2014 Property
Real Estate [Abstract]
Number of industrial properties acquired	2
Gross leasable area (GLA) of industrial properties acquired | ft²	200
Purchase price of acquisitions | $	$ 26,532
Number of industrial properties held for sale	1
Gross leasable area (GLA) of industrial properties held for sale | ft²	10
Number of industrial properties sold	12
Gross leasable area (GLA) of industrial properties sold | ft²	900
Number of land parcels sold | Land_Parcel	1
Proceeds from the sale of industrial properties | $	$ 42,611
Gain on sale of real estate | $	$ 10,127	$ 1,055
Number of sold industrial properties included in discontinued operations		5	29