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Fair Value of Financial Instruments - Additional Information (Detail)
$ in Thousands
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Jun. 30, 2011
instrument
Fair Value of Financial Instruments [Line Items]      
Interest rate 3.90% 4.25%  
Notes payable, fair value $ 951,700 $ 851,300  
Fixed rate mortgages 897,888 783,400  
Interest rate swap      
Fair Value of Financial Instruments [Line Items]      
Fair value of derivative liability $ 1,100    
Cash flow hedging | Designated as hedging instrument | Interest rate swap      
Fair Value of Financial Instruments [Line Items]      
Derivative, number of instruments held | instrument     1
Fixed rate mortgage notes payable      
Fair Value of Financial Instruments [Line Items]      
Interest rate 5.25%    
Fixed rate mortgages $ 890,393 $ 844,292