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Unit-Based Compensation Additional Information (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Units available for delivery (in shares) 800,000    
Term of approved plan (in years) 10 years    
Vesting period of Grants (in years) 3 years    
Grant date fair value $ 3.5 $ 5.4 $ 2.2
Unaccrued Cost Associated With Outstanding Grants And Related Distribution Equivalent Rights $ 3.7 3.5  
Weighted average recognition period (in years) 1 year 7 months 6 days    
Director      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period of Grants (in years) 1 year    
General and Administrative expenses and Operating and Maintenance expenses      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Compensation expense $ 3.6 $ 2.4 $ 1.1