Annual report pursuant to Section 13 and 15(d)

Real Estate Dispositions, Held for Sale, and Impairment Charges - Additional Information (Detail)

v3.8.0.1
Real Estate Dispositions, Held for Sale, and Impairment Charges - Additional Information (Detail)
$ in Thousands
3 Months Ended 12 Months Ended
Sep. 30, 2017
USD ($)
Jun. 30, 2017
USD ($)
Mar. 31, 2017
USD ($)
Dec. 31, 2017
USD ($)
property
Dec. 31, 2016
USD ($)
property
Dec. 31, 2015
USD ($)
property
Schedule Of Real Estate Owned Held For Sale [Line Items]            
Number of impaired assets, held and used       2 1  
Impairment charge | $     $ 3,700 $ 6,835 $ 2,016 $ 622
Gain (loss) on sale of real estate, net | $ $ 1 $ (1,800)   $ 3,993 $ 242 $ 1,538
Discontinued Operations, Held-for-sale or Disposed of by Sale [Member]            
Schedule Of Real Estate Owned Held For Sale [Line Items]            
Number of real estates properties classified as held for sale during period       2    
Held-for-sale            
Schedule Of Real Estate Owned Held For Sale [Line Items]            
Impairment charge | $       $ 3,100    
Number of impaired assets classified as held for sale during period       2 1 1
Number of impaired Assets         7  
Number of impaired assets sold         5