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Earnings Per Common Share - Additional Information (Detail) - USD ($)
3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Dec. 31, 2016
Feb. 29, 2016
Sep. 30, 2015
Jun. 21, 2013
Earnings Per Share [Line Items]            
Average share price (in dollars per share) $ 75.47 $ 86.91        
Principal amount of notes outstanding $ 612,233,000   $ 610,314,000      
Series A Units [Member]            
Earnings Per Share [Line Items]            
Exchangeable preferred operating partnership units settled in cash, minimum 115,000,000          
Operating Partnership [Member] | Exchangeable Senior Notes 2.375% due 2033 (the 2013 Notes) [Member]            
Earnings Per Share [Line Items]            
Principal amount of notes outstanding $ 63,170,000   63,170,000 $ 19,639,000    
Interest rate 2.375%         2.375%
Exchange price (in dollars per share) $ 53.81          
Shares related to the Notes included in the computation for diluted earnings per share (in shares) 336,848 441,598        
Operating Partnership [Member] | Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes) [Member]            
Earnings Per Share [Line Items]            
Principal amount of notes outstanding $ 575,000,000   $ 575,000,000      
Interest rate 3.125%       3.125%  
Exchange price (in dollars per share) $ 94.47          
Shares related to the Notes included in the computation for diluted earnings per share (in shares) 0 0        
Stock Options [Member]            
Earnings Per Share [Line Items]            
Anti-dilutive securities excluded from computation of earnings per common share (in shares) 103,854 67,812