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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, 2018
USD ($)
vesting_installment
shares
Feb. 28, 2018
USD ($)
vesting_installment
shares
Mar. 31, 2018
USD ($)
$ / shares
shares
Mar. 31, 2017
USD ($)
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Weighted-average per unit or share fair value (in USD per share) | $ / shares     $ 8.38    
Expected volatility rate look-back period     6 years    
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          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Noncash share-based compensation expense recognized | $     $ 1.2 $ 0.6  
Unrecognized compensation expense | $ $ 1.3   $ 1.3    
Unrecognized compensation expense, period for recognition     2 years 6 months 24 days    
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 | $     $ 3.4 $ 2.6  
Unrecognized compensation expense | $ $ 40.5   $ 40.5    
Unrecognized compensation expense, period for recognition     2 years 8 months 1 day    
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 | $     $ 22.6    
Weighted-average per unit or share fair value (in USD per share) | $ / shares     $ 8.38    
Risk free interest rate (as a percent)     2.50%    
Expected volatility rate (as a percent)     17.00%    
LTIP Units          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares granted (in shares)     2,654,801    
Time Based Long-Tern Incentive Plan Unit | 2013 Plan Units, granted in March 2018          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares granted (in shares) 67,449        
Fair value of share-based awards granted in period | $ $ 1.7        
Number of vesting installments | vesting_installment 3        
Award vesting period 4 years        
Performance Based Long-Term Incentive Plan Unit | 2013 Plan Units, granted in March 2018          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares granted (in shares) 223,950        
Fair value of share-based awards granted in period | $ $ 1.1        
Number of vesting installments | vesting_installment 2        
Award vesting period 3 years        
Restricted Stock          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares granted (in shares)     39,608    
Time Restricted Shares | 2013 Plan Units, granted in March 2018          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares granted (in shares) 39,608        
Long-Term Incentive Plan Unit and Restricted Stock          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Expected term     5 years 6 months 24 days    
Dividend rate (as a percent)     2.30%    
Executive Officer | Time Based Long-Tern Incentive Plan Unit | 2013 Plan Units, granted in March 2018          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares granted (in shares) 386,876        
Fair value of share-based awards granted in period | $ $ 6.1        
Executive Officer | Time Based Long-Tern Incentive Plan Unit | 2013 Plan Units, granted in February 2018          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares granted (in shares)   238,609      
Fair value of share-based awards granted in period | $   $ 4.0      
Award vesting period         3 years
Vesting percentage of award face amount         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)   25,158      
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)   213,451      
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, granted in March 2018          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares granted (in shares) 1,737,917        
Fair value of share-based awards granted in period | $ $ 9.6        
2013 Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Number of shares authorized under the plan (in shares) 12,200,000.0   12,200,000.0    
Number of shares that remain available for future issuance (in shares) 4,400,000   4,400,000