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Distributions - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 1 Months Ended 12 Months Ended
Jan. 31, 2017
Jan. 13, 2017
Jan. 06, 2017
Dec. 31, 2016
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Dividends [Line Items]              
Common stock issued, discount rate         3.00%    
Common stock distributions (in usd per share)         $ 1.84 $ 1.69 $ 1.56
Dividends declared per common share outstanding (in usd per share)       $ 0.51      
Distribution to limited partnership unitholders         $ 13,533 $ 12,228 $ 11,117
Dividend Income              
Dividends [Line Items]              
Common stock distributions (in usd per share)         $ 1.75 $ 1.69 $ 1.56
Return on Invested Capital              
Dividends [Line Items]              
Return of capital (in USD per share)       $ 0.09 0.09    
Series A Preferred Stock              
Dividends [Line Items]              
Preferred stock dividend (in usd per share)             2.41
Series C Preferred Stock              
Dividends [Line Items]              
Preferred stock dividend (in usd per share)         $ 1.72 $ 1.72 $ 1.72
Subsequent Event              
Dividends [Line Items]              
Common stock dividend paid $ 11,000            
Distribution to limited partnership unitholders $ 3,800            
Distributions partnership units (in usd per share) $ 0.51            
Subsequent Event | Series C Preferred Stock              
Dividends [Line Items]              
Dividends declared per preferred share outstanding (in usd per share)     $ 0.4297        
Preferred stock distributions   $ 3,100