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COMMON UNIT-BASED COMPENSATION PLANS - LTIP Grants (Details) - ARLP LTIP - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Jan. 24, 2024
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Dec. 31, 2020
Number of units          
Balance at the beginning of the period (in units)   3,697,133 3,130,475 1,430,489  
Granted (in units) 425,470 450,125 769,907 1,818,190  
Vested (in units)   (1,291,330)      
Forfeited (in units)   (145,584) (203,249) (118,204)  
Balance at the end of the period (in units)   2,710,344 3,697,133 3,130,475  
Weighted average grant date fair value per unit          
Balance at the beginning of the period (in dollars per unit)   $ 7.40 $ 5.59 $ 5.02  
Granted (in dollars per unit)   21.54 14.65 6.03  
Vested (in dollars per unit)   5.02      
Forfeited (in dollars per unit)   6.86 6.93 5.48  
Balance at the end of the period (in dollars per unit)   $ 10.91 $ 7.40 $ 5.59  
Intrinsic value (in dollars)          
Intrinsic value of outstanding grants (in dollars)   $ 57,405 $ 75,126 $ 39,569 $ 6,409
Other information          
Common units issued   860,060