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COMPENSATION PLANS (Tables) | 9 Months Ended
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Sep. 30, 2020
ARLP LTIP |
Compensation Plans |
Summary of activity in share-based plans | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ |  | Number of units |  | Weighted average grant date fair value per unit |
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
Non-vested grants at January 1, 2020 | ​ | 1,603,378 | ​ | ​ | ​ | ​
Granted |  | 950,035 | ​ | $ | 9.62 | ​
Vested (1) |  | (424,486) | ​ |  | 23.22 | ​
Forfeited |  | (13,835) | ​ |  | 16.13 | ​
Non-vested grants at September 30, 2020 (2) |  | 2,115,092 | ​ |  | ​ | ​
(1) | During the nine months ended September 30, 2020, we issued 279,622 unrestricted common units to the LTIP participants. The remaining vested units were settled in cash to satisfy tax withholding obligations of the LTIP participants.
(2) | Represents total non-vested grants outstanding including 675,302 restricted units that were granted in 2019 (the "2019 Grants"). During the First Quarter, it was determined that the vesting requirements for the 2019 Grants were not probable of being satisfied.
SERP and Directors' Compensation Plans |
Compensation Plans |
Summary of activity in share-based plans | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ |  | Number of units |  | Weighted average grant date fair value per unit |  | Intrinsic value |
​ | ​ | ​ | ​ | ​ | ​ | ​ | (in thousands) | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Phantom units outstanding as of January 1, 2020 | ​ | 631,365 | ​ | $ | 25.48 | ​ | $ | 6,831 | ​
Granted | ​ | 29,544 | ​ | ​ | 7.87 | ​ | ​ | ​ | ​
Phantom units outstanding as of September 30, 2020 |  | 660,909 | ​ |  | 24.69 | ​ | ​ | 1,831 | ​

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