Quarterly report pursuant to Section 13 or 15(d)

Real Estate and Intangible Assets - Schedule of Revenue and Earnings Recognized on Properties Acquired (Detail)

v3.3.0.814
Real Estate and Intangible Assets - Schedule of Revenue and Earnings Recognized on Properties Acquired (Detail) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2015
Sep. 30, 2014
Sep. 30, 2015
Sep. 30, 2014
Business Acquisition [Line Items]        
Rental Revenue $ 1,762 $ 2,105 $ 2,971 $ 3,016
Earnings 469 1,047 $ 1,328 $ 1,422
Richardson, TX [Member]        
Business Acquisition [Line Items]        
Acquisition Date     Mar. 06, 2015  
Rental Revenue 656   $ 1,496  
Earnings 96   $ 423  
Birmingham, AL [Member]        
Business Acquisition [Line Items]        
Acquisition Date     Mar. 20, 2015  
Rental Revenue 83   $ 177  
Earnings (22)   $ 84  
Columbus, OH [Member]        
Business Acquisition [Line Items]        
Acquisition Date     May 28, 2015 May 13, 2014
Rental Revenue 177 311 $ 244 $ 479
Earnings 18 115 $ 166 $ 184
Salt Lake City, UT [Member]        
Business Acquisition [Line Items]        
Acquisition Date     May 29, 2015  
Rental Revenue 572   $ 780  
Earnings 163   $ 441  
Atlanta, GA [Member]        
Business Acquisition [Line Items]        
Acquisition Date     Jul. 15, 2015  
Rental Revenue 274   $ 274  
Earnings $ 214   $ 214  
Allen, TX [Member]        
Business Acquisition [Line Items]        
Acquisition Date       Mar. 27, 2014
Rental Revenue   143   $ 293
Earnings   101   $ 167
Colleyville, TX [Member]        
Business Acquisition [Line Items]        
Acquisition Date       Mar. 27, 2014
Rental Revenue   117   $ 240
Earnings   83   $ 138
Rancho Cordova, CA [Member]        
Business Acquisition [Line Items]        
Acquisition Date       Apr. 22, 2014
Rental Revenue   226   $ 399
Earnings   104   $ 168
Coppell, TX [Member]        
Business Acquisition [Line Items]        
Acquisition Date       May 08, 2014
Rental Revenue   150   $ 239
Earnings   116   $ 139
Taylor, PA [Member]        
Business Acquisition [Line Items]        
Acquisition Date       Jun. 09, 2014
Rental Revenue   850   $ 1,058
Earnings   395   $ 493
Aurora, CO [Member]        
Business Acquisition [Line Items]        
Acquisition Date       Jul. 01, 2014
Rental Revenue   192   $ 192
Earnings   124   $ 124
Indianapolis, IN [Member]        
Business Acquisition [Line Items]        
Acquisition Date       Sep. 03, 2014
Rental Revenue   116   $ 116
Earnings   $ 9   $ 9