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Earnings Per Common Share - Additional Information (Detail) - USD ($)
3 Months Ended 6 Months Ended
Jul. 05, 2018
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Dec. 31, 2017
Sep. 30, 2015
Jun. 21, 2013
Earnings Per Share [Line Items]                
Average share price (in dollars per share)   $ 93.10 $ 76.68 $ 88.71 $ 76.08      
Principal amount of notes outstanding   $ 570,425,000   $ 570,425,000   $ 604,276,000    
Operating Partnership | Exchangeable Senior Notes 2.375% due 2033 (the 2013 Notes)                
Earnings Per Share [Line Items]                
Principal amount of notes outstanding   $ 11,550,000   $ 11,550,000   49,259,000    
Debt stated interest rate   2.375%   2.375%       2.375%
Exchange price (in dollars per share)   $ 52.57   $ 52.57        
Total consideration paid for repurchase       $ 58,469,000        
Shares related to the Notes included in the computation for diluted earnings per share (in shares)   95,690 95,690 356,000 356,000      
Operating Partnership | Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes)                
Earnings Per Share [Line Items]                
Principal amount of notes outstanding   $ 575,000,000   $ 575,000,000   $ 575,000,000    
Debt stated interest rate   3.125%   3.125%     3.125%  
Exchange price (in dollars per share)   $ 93.34   $ 93.34        
Shares related to the Notes included in the computation for diluted earnings per share (in shares)   0 0 0 0      
Stock Options                
Earnings Per Share [Line Items]                
Anti-dilutive securities excluded from computation of earnings per common share (in shares)   0 97,701 37,113 98,966      
Series A Units                
Earnings Per Share [Line Items]                
Exchangeable preferred operating partnership units settled in cash, minimum   $ 101,700,000   $ 101,700,000        
Subsequent Event [Member] | Operating Partnership | Exchangeable Senior Notes 2.375% due 2033 (the 2013 Notes)                
Earnings Per Share [Line Items]                
Total consideration paid for repurchase $ 21,801,000