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Share and Unit-based Plans - Long-Term Incentive Plan Units (Details)
12 Months Ended
Jun. 01, 2017
$ / shares
shares
Mar. 03, 2017
$ / shares
shares
Jan. 01, 2017
$ / shares
shares
Mar. 04, 2016
$ / shares
shares
Jan. 07, 2016
Jan. 01, 2016
$ / shares
shares
Dec. 31, 2015
shares
Mar. 06, 2015
$ / shares
shares
Jan. 01, 2015
$ / shares
shares
Jan. 01, 2014
Dec. 31, 2017
$ / shares
shares
Dec. 31, 2016
$ / shares
shares
Dec. 31, 2015
$ / shares
shares
Stock units                          
Share and unit-based plans                          
Conversion rate                     1    
Granted (shares)                     86,827 85,601 77,282
Granted (in dollars per share) | $ / shares                     $ 66.46 $ 79.22 $ 86.53
Vested (shares)                     81,205 69,259 86,761
LTIP units                          
Share and unit-based plans                          
Conversion rate                     1    
Granted (shares)                     506,906 480,371 424,442
Granted (in dollars per share) | $ / shares                     $ 55.33 $ 65.00 $ 74.71
Absolute return requirement (shares)                   3.00%      
Risk free rate (as a percent) 1.45%   1.49%     1.32%     0.25%        
Volatility rate (as a percent) 21.40%   20.75%     20.31%     16.81%        
Level of percentile ranking at which awards vested (as a percent)         130.00%                
Vested (shares)             55,934       192,846 214,114 414,822
LTIP units | LTIP units that vest in equal installments over a service period ending December 31, 2018                          
Share and unit-based plans                          
Granted (shares) 1,522   66,079     58,786              
Granted (in dollars per share) | $ / shares $ 58.31   $ 70.84     $ 80.69              
LTIP units | Market-Indexed LTIP units that vest in equal installments over a service period ending December 31, 2018                          
Share and unit-based plans                          
Granted (shares) 6,714   297,849     266,899              
Granted (in dollars per share) | $ / shares $ 39.66   $ 47.15     $ 53.32              
LTIP units | LTIP units that are fully vested on the grant date                          
Share and unit-based plans                          
Granted (shares)   134,742   154,686                  
Granted (in dollars per share) | $ / shares   $ 66.57   $ 79.20                  
LTIP units | 2015 LTIP Units Series 1                          
Share and unit-based plans                          
Granted (shares)                 49,451        
Granted (in dollars per share) | $ / shares                 $ 83.41        
LTIP units | 2015 LTIP Units Series 2                          
Share and unit-based plans                          
Granted (shares)                 186,450        
Granted (in dollars per share) | $ / shares                 $ 66.37        
LTIP units | 2015 LTIP Units Series 3                          
Share and unit-based plans                          
Granted (shares)               132,607          
Granted (in dollars per share) | $ / shares               $ 86.72