Quarterly report pursuant to Section 13 or 15(d)

Real Estate and Intangible Assets - Fair Value of Acquired Assets (Detail)

v3.2.0.727
Real Estate and Intangible Assets - Fair Value of Acquired Assets (Detail) - USD ($)
$ in Thousands
 6 Months Ended
Jun. 30, 2015
Jun. 30, 2014
Business Acquisition [Line Items]    
Total Purchase Price $ 58,248 $ 74,911
Customer Relationships [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 4,520 4,767
Above Market Leases [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 1,796 261
Below Market Leases [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired (1,132) (6)
Premium on Assumed Debt [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   (249)
Richardson, TX [Member]    
Business Acquisition [Line Items]    
Total Purchase Price 24,700  
Richardson, TX [Member] | Customer Relationships [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 1,915  
Richardson, TX [Member] | Above Market Leases [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 975  
Birmingham, AL [Member]    
Business Acquisition [Line Items]    
Total Purchase Price 3,648  
Birmingham, AL [Member] | Customer Relationships [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 360  
Allen, TX [Member]    
Business Acquisition [Line Items]    
Total Purchase Price   5,525
Allen, TX [Member] | Customer Relationships [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   218
Allen, TX [Member] | Premium on Assumed Debt [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   (72)
Colleyville, TX [Member]    
Business Acquisition [Line Items]    
Total Purchase Price   4,523
Colleyville, TX [Member] | Customer Relationships [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   181
Colleyville, TX [Member] | Below Market Leases [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   (6)
Colleyville, TX [Member] | Premium on Assumed Debt [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   (59)
Rancho Cordova, CA [Member]    
Business Acquisition [Line Items]    
Total Purchase Price   8,225
Rancho Cordova, CA [Member] | Customer Relationships [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   278
Coppell, TX [Member]    
Business Acquisition [Line Items]    
Total Purchase Price   5,838
Coppell, TX [Member] | Customer Relationships [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   230
Coppell, TX [Member] | Premium on Assumed Debt [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   (118)
Columbus, OH [Member]    
Business Acquisition [Line Items]    
Total Purchase Price 7,700 11,800
Columbus, OH [Member] | Customer Relationships [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 567 990
Columbus, OH [Member] | Above Market Leases [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   261
Columbus, OH [Member] | Below Market Leases [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired (1,079)  
Taylor, PA [Member]    
Business Acquisition [Line Items]    
Total Purchase Price   39,000
Taylor, PA [Member] | Customer Relationships [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   2,870
Salt Lake City, UT [Member]    
Business Acquisition [Line Items]    
Total Purchase Price 22,200  
Salt Lake City, UT [Member] | Customer Relationships [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 1,678  
Salt Lake City, UT [Member] | Above Market Leases [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 821  
Salt Lake City, UT [Member] | Below Market Leases [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired (53)  
Land [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 7,945 8,443
Land [Member] | Richardson, TX [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 2,709  
Land [Member] | Birmingham, AL [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 650  
Land [Member] | Allen, TX [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   874
Land [Member] | Colleyville, TX [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   1,277
Land [Member] | Rancho Cordova, CA [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   752
Land [Member] | Coppell, TX [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   1,448
Land [Member] | Columbus, OH [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 1,338 990
Land [Member] | Taylor, PA [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   3,102
Land [Member] | Salt Lake City, UT [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 3,248  
Building [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 29,558 45,464
Building [Member] | Richardson, TX [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 12,503  
Building [Member] | Birmingham, AL [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 1,683  
Building [Member] | Allen, TX [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   3,509
Building [Member] | Colleyville, TX [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   2,307
Building [Member] | Rancho Cordova, CA [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   5,898
Building [Member] | Coppell, TX [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   3,221
Building [Member] | Columbus, OH [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 3,511 6,080
Building [Member] | Taylor, PA [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   24,449
Building [Member] | Salt Lake City, UT [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 11,861  
Tenant Improvements [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 5,927 3,541
Tenant Improvements [Member] | Richardson, TX [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 2,761  
Tenant Improvements [Member] | Birmingham, AL [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 351  
Tenant Improvements [Member] | Allen, TX [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   125
Tenant Improvements [Member] | Colleyville, TX [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   117
Tenant Improvements [Member] | Rancho Cordova, CA [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   278
Tenant Improvements [Member] | Coppell, TX [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   128
Tenant Improvements [Member] | Columbus, OH [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 1,547 1,937
Tenant Improvements [Member] | Taylor, PA [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   956
Tenant Improvements [Member] | Salt Lake City, UT [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 1,268  
In-Place Leases [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 6,044 9,187
In-Place Leases [Member] | Richardson, TX [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 2,046  
In-Place Leases [Member] | Birmingham, AL [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 458  
In-Place Leases [Member] | Allen, TX [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   598
In-Place Leases [Member] | Colleyville, TX [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   486
In-Place Leases [Member] | Rancho Cordova, CA [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   473
In-Place Leases [Member] | Coppell, TX [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   636
In-Place Leases [Member] | Columbus, OH [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 1,144 823
In-Place Leases [Member] | Taylor, PA [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   6,171
In-Place Leases [Member] | Salt Lake City, UT [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 2,396  
Leasing Costs [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 3,590 3,503
Leasing Costs [Member] | Richardson, TX [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 1,791  
Leasing Costs [Member] | Birmingham, AL [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 146  
Leasing Costs [Member] | Allen, TX [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   273
Leasing Costs [Member] | Colleyville, TX [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   220
Leasing Costs [Member] | Rancho Cordova, CA [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   546
Leasing Costs [Member] | Coppell, TX [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   293
Leasing Costs [Member] | Columbus, OH [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired 672 719
Leasing Costs [Member] | Taylor, PA [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired   $ 1,452
Leasing Costs [Member] | Salt Lake City, UT [Member]    
Business Acquisition [Line Items]    
Fair value of acquired assets related to the properties acquired $ 981