XML 50 R40.htm IDEA: XBRL DOCUMENT v3.19.2
Earnings Per Common Share - Additional Information (Detail) - USD ($)
3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Dec. 31, 2018
Sep. 30, 2015
Jun. 21, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]              
Average share price (in dollars per share) $ 105.06 $ 93.10 $ 100.63 $ 88.71      
Principal amount of notes outstanding $ 565,920,000   $ 565,920,000   $ 562,374,000    
Exchangeable Senior Notes 2.375% due 2033 (the 2013 Notes)              
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]              
Principal amount of notes outstanding $ 0   $ 0        
Debt stated interest rate 2.375%   2.375%       2.375%
Shares related to the Notes included in the computation for diluted earnings per share (in shares) 0 95,690          
Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes)              
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]              
Principal amount of notes outstanding $ 575,000,000   $ 575,000,000        
Debt stated interest rate 3.125%   3.125%     3.125%  
Exchange price (in dollars per share) $ 92.28   $ 92.28        
Shares related to the Notes included in the computation for diluted earnings per share (in shares) 757,811 0          
Series A Units              
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]              
Exchangeable preferred operating partnership units settled in cash, minimum $ 101,700,000   $ 101,700,000        
Stock Options              
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]              
Anti-dilutive securities excluded from computation of earnings per common share (in shares) 0 0 0 37,113