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Equity - 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]          
Expected volatility rate look-back period     6 years    
Weighted-average per unit or share fair value (in USD per share) | $ / shares     $ 8.38    
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    
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    
Long-Term Incentive Plan Unit and Restricted Stock          
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    
Expected term     5 years 6 months 24 days    
Dividend rate (as a percent)     2.30%    
Risk-free interest rate (as a percent)     2.50%    
Expected price volatility (as a percent)     17.00%    
Long-Term Incentive Plan Unit          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Granted (in shares)     2,654,801    
Restricted Stock          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Granted (in shares)     39,608    
2013 Plan Units, granted in March 2018 | Time Based Long-Tern Incentive Plan Unit          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Granted (in shares) 67,449        
Fair value of share-based awards granted in period | $ $ 1.7        
Award vesting period 4 years        
Number of vesting installments | vesting_installment 3        
2013 Plan Units, granted in March 2018 | Performance Based Long-Term Incentive Plan Unit          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Granted (in shares) 223,950        
Fair value of share-based awards granted in period | $ $ 1.1        
Award vesting period 3 years        
Number of vesting installments | vesting_installment 2        
2013 Plan Units, granted in March 2018 | Time Restricted Shares          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Granted (in shares) 39,608        
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 7 months 12 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 12 days    
Executive Officer | 2013 Plan Units, granted in March 2018 | Time Based Long-Tern Incentive Plan Unit          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Granted (in shares) 386,876        
Fair value of share-based awards granted in period | $ $ 6.1        
Executive Officer | 2013 Plan Units, granted in March 2018 | Performance Based Long-Term Incentive Plan Unit          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Granted (in shares) 1,737,917        
Fair value of share-based awards granted in period | $ $ 9.6        
Executive Officer | 2013 Plan Units, granted in February 2018 | Time Based Long-Tern Incentive Plan Unit          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
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 | Vest immediately | Time Based Long-Tern Incentive Plan Unit          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Granted (in shares)   25,158      
Executive Officer | Vest ratably over three years | Time Based Long-Tern Incentive Plan Unit          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Granted (in shares)   213,451      
Award vesting period   3 years      
Executive Officer | Vest in two equal annual installments | Time Based Long-Tern Incentive Plan Unit          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Number of vesting installments | vesting_installment   2