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Capital - Incentive and Share-based Compensation (Details)
$ / shares in Units, $ in Millions
1 Months Ended 3 Months Ended 12 Months Ended
Mar. 31, 2017
USD ($)
vesting_installment
$ / shares
shares
Jun. 30, 2016
USD ($)
shares
Feb. 29, 2016
USD ($)
vesting_installment
shares
Mar. 31, 2017
USD ($)
$ / shares
shares
Mar. 31, 2016
USD ($)
$ / shares
Dec. 31, 2016
USD ($)
$ / shares
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Expected volatility rate look-back period (in years)       6 years    
Weighted Average Grant Fair Value [Roll Forward]            
Beginning balance, Unvested, Weighted Average Grant Fair Value (in USD per share) | $ / shares       $ 10.01    
Vested, Weighted Average Grant Fair Value (in USD per share) | $ / shares       13.19    
Granted, Weighted Average Grant Fair Value (in USD per share) | $ / shares       13.55    
Forfeited or unearned, Weighted Average Grant Fair Value (in USD per share) | $ / shares       14.87    
Ending balance, Unvested, Weighted Average Grant Fair Value (in USD per share) | $ / shares $ 10.89     $ 10.89   $ 10.01
Age of grantee at which LTIP unit and restricted stock awards immediately vest       60 years    
Period of service, upon completion of which, grantee's LTIP unit and restricted stock awards will immediately vest       10 years    
Awards that Meet Age and Service Requirements for Vesting            
Weighted Average Grant Fair Value [Roll Forward]            
Noncash share-based compensation expense recognized | $       $ 0.6 $ 0.4  
Unrecognized compensation expense | $ $ 1.2     $ 1.2    
Unrecognized compensation expense, period for recognition (in years)       2 years 8 months 18 days    
Awards that Do Not Meet Age and Service Requirements for Vesting            
Weighted Average Grant Fair Value [Roll Forward]            
Noncash share-based compensation expense recognized | $       $ 2.6 1.7  
Unrecognized compensation expense | $ $ 32.9     $ 32.9    
Unrecognized compensation expense, period for recognition (in years)       2 years 10 months 18 days    
Long-Term Incentive Plan Units and Restricted Stock [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Fair value of share-based awards granted in period | $       $ 18.4 $ 17.5  
Risk free interest rate       1.55% 0.84%  
Expected volatility rate       20.00% 24.00%  
Weighted Average Grant Fair Value [Roll Forward]            
Granted, Weighted Average Grant Fair Value (in USD per share) | $ / shares       $ 13.55 $ 9.38  
Long-Term Incentive Plan Unit [Member]            
Restricted Stock and LTIP Unit Activity [Roll Forward]            
Beginning balance, Unvested (in shares)       2,881,629    
Vested (in shares)       (271,136)    
Granted (in shares)       1,322,166    
Forfeited or unearned (in shares)       (77,227)    
Ending balance, Unvested (in shares) 3,855,432     3,855,432   2,881,629
Time Based Long-Tern Incentive Plan Unit            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Fair value of share-based awards granted in period | $ $ 1.6   $ 1.4     $ 0.1
Restricted Stock and LTIP Unit Activity [Roll Forward]            
Granted (in shares) 47,993   47,168      
Performance Based Long-Term Incentive Plan Unit            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Fair value of share-based awards granted in period | $ $ 1.0   $ 0.8      
Restricted Stock and LTIP Unit Activity [Roll Forward]            
Granted (in shares) 95,156   112,925      
Restricted Stock            
Restricted Stock and LTIP Unit Activity [Roll Forward]            
Beginning balance, Unvested (in shares)       107,793    
Vested (in shares)       (16,577)    
Granted (in shares)       34,407    
Forfeited or unearned (in shares)       (1,404)    
Ending balance, Unvested (in shares) 124,219     124,219   107,793
Time Restricted Shares            
Restricted Stock and LTIP Unit Activity [Roll Forward]            
Granted (in shares) 34,407   44,198      
Long-Term Incentive Plan Unit and Restricted Stock            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Expected term       2 years 9 months 18 days 2 years 9 months 18 days  
Dividend rate       2.05% 2.10%  
Executive Officer | Time Based Long-Tern Incentive Plan Unit | 2013 Plan Units Vesting January 2019            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Fair value of share-based awards granted in period | $     $ 5.6      
Number of vesting installments | vesting_installment     3      
Award vesting period (in years)     4 years      
Restricted Stock and LTIP Unit Activity [Roll Forward]            
Granted (in shares)     368,225      
Executive Officer | Time Based Long-Tern Incentive Plan Unit | 2013 Plan Units Vesting three years after February 2016            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Fair value of share-based awards granted in period | $     $ 1.0      
Award vesting percentage after three years     30.00%      
Award vesting percentage after four years     30.00%      
Award vesting percentage after five years     40.00%      
Restricted Stock and LTIP Unit Activity [Roll Forward]            
Granted (in shares)     62,814      
Executive Officer | Time Based Long-Tern Incentive Plan Unit | 2013 Plan Units, granted in March 2017            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Fair value of share-based awards granted in period | $ $ 6.1          
Number of vesting installments | vesting_installment 3          
Award vesting period (in years) 4 years          
Restricted Stock and LTIP Unit Activity [Roll Forward]            
Granted (in shares) 313,275          
Executive Officer | Performance Based Long-Term Incentive Plan Unit | 2013 Plan Units Vesting January 2019            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Fair value of share-based awards granted in period | $     $ 8.8      
Number of vesting installments | vesting_installment     2      
Award vesting period (in years)     3 years      
Restricted Stock and LTIP Unit Activity [Roll Forward]            
Granted (in shares)     1,230,228      
Executive Officer | Performance Based Long-Term Incentive Plan Unit | 2013 Plan Units, granted in March 2017            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Fair value of share-based awards granted in period | $ $ 9.6          
Number of vesting installments | vesting_installment 2          
Award vesting period (in years) 3 years          
Restricted Stock and LTIP Unit Activity [Roll Forward]            
Granted (in shares) 865,742          
Director | Time Based Long-Tern Incentive Plan Unit | 2013 Plan Units Vesting three years after June 2016            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Fair value of share-based awards granted in period | $   $ 0.8        
Award vesting period (in years)   3 years        
Restricted Stock and LTIP Unit Activity [Roll Forward]            
Granted (in shares)   43,257        
2013 Plan            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Number of shares authorized under the plan (shares) 12,200,000.0     12,200,000.0    
Number of shares that remain available for future issuance (shares) 7,000,000     7,000,000