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Capital - Incentive and Share-based Compensation (Details)
$ / shares in Units, $ in Millions
1 Months Ended 3 Months Ended
Mar. 31, 2019
USD ($)
vesting_installment
shares
Mar. 31, 2019
USD ($)
$ / shares
shares
Mar. 31, 2018
USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected volatility rate look-back period (in years)   6 years  
Weighted-average per unit or share fair value (in USD per share) | $ / shares   $ 9.42  
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 (in years)   10 years  
Awards that meet age and service requirements for vesting      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Noncash share-based compensation expense recognized | $   $ 1.3 $ 1.2
Unrecognized compensation expense | $ $ 1.8 $ 1.8  
Unrecognized compensation expense, period for recognition   2 years 7 months  
Awards that do not meet age and service requirements for vesting      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Noncash share-based compensation expense recognized | $   $ 4.1 $ 3.4
Unrecognized compensation expense | $ $ 47.9 $ 47.9  
Unrecognized compensation expense, period for recognition   2 years 8 months  
Long-Term Incentive Plan Units and Restricted Stock      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Fair value of share-based awards granted in period | $   $ 26.8  
Weighted-average per unit or share fair value (in USD per share) | $ / shares   $ 9.42  
Dividend rate (as a percent)   2.40%  
Risk free interest rate, minimum (as a percent)   2.48%  
Risk free interest rate, maximum (as a percent)   2.63%  
Expected price volatility, minimum (as a percent)   17.00%  
Expected price volatility, maximum (as a percent)   22.00%  
Time Based Long-Tern Incentive Plan Unit | 2013 Plan Units      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares granted (in shares) | shares 61,432    
Fair value of share-based awards granted in period | $ $ 2.0    
Award vesting period 4 years    
Number of vesting installments | vesting_installment 3    
Performance Based Long-Term Incentive Plan Unit | 2013 Plan Units      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares granted (in shares) | shares 113,383    
Fair value of share-based awards granted in period | $ $ 0.9    
Award vesting period 3 years    
Number of vesting installments | vesting_installment 2    
Time Restricted Shares | 2013 Plan Units      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares granted (in shares) | shares 69,358    
Executive Officer | Time Based Long-Tern Incentive Plan Unit | 2013 Plan Units      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares granted (in shares) | shares 461,693    
Fair value of share-based awards granted in period | $ $ 6.4    
Executive Officer | Time Based Long-Tern Incentive Plan Unit | 2013 Plan Units, connected with bonus program      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares granted (in shares) | shares 334,952    
Fair value of share-based awards granted in period | $ $ 4.6    
Award vesting period   3 years  
Vesting percentage of award face amount 125.00% 125.00%  
Executive Officer | Time Based Long-Tern Incentive Plan Unit | Vesting immediately      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares granted (in shares) | shares 26,056    
Executive Officer | Time Based Long-Tern Incentive Plan Unit | Vest ratably over three years      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares granted (in shares) | shares 308,896    
Award vesting period 3 years    
Executive Officer | Time Based Long-Tern Incentive Plan Unit | Vest in two equal annual installments      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of vesting installments | vesting_installment 2    
Executive Officer | Performance Based Long-Term Incentive Plan Unit | 2013 Plan Units      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares granted (in shares) | shares 1,806,520    
Fair value of share-based awards granted in period | $ $ 12.8    
2013 Plan      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of shares authorized under the plan (in shares) | shares 12,200,000.0 12,200,000.0  
Number of shares that remain available for future issuance (in shares) | shares 2,800,000 2,800,000  
Minimum | Long-Term Incentive Plan Units and Restricted Stock      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term   2 years  
Maximum | Long-Term Incentive Plan Units and Restricted Stock      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term   5 years 4 months