v3.20.4
UNIT-BASED COMPENSATION Table 1 - Information for LTIP Plans (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Unit-based awards, outstanding (units) 2,441,003 1,456,296 1,277,480  
Compensation expense $ 12,185 $ 38,035 $ 30,699  
Restricted units, domestic employees [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Unit-based awards, outstanding (units) 2,235,125 1,223,143 1,028,484 736,746
Compensation expense $ 10,205 $ 9,437 $ 8,233  
Restricted units, non-employee directors [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Unit-based awards, outstanding (units) 98,769 61,349 59,752 27,097
Compensation expense $ 631 $ 774 $ 524  
Restricted units, international employees [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Unit-based awards, outstanding (units) 19,987 10,243 30,918  
Compensation expense $ 58 $ 711 $ 1,158  
Performance Units [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Unit-based awards, outstanding (units) 57,448 74,439 80,690 38,865
Compensation expense $ 1,291 $ 4,172 $ 1,889  
Performance units awarded and outstanding 87,122 161,561 158,326 80,961
Unit Awards[Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Compensation expense $ 0 $ 22,941 $ 18,895  
Performance units awarded and outstanding 0 0 0