We maintain the LTIP for certain employees and officers of MGP and its affiliates who perform services for us. The LTIP awards are grants of non-vested "phantom" or notional units, also referred to as "restricted units", which upon satisfaction of time and performance-based vesting requirements, entitle the LTIP participant to receive ARLP common units. Annual grant levels and vesting provisions for designated participants are recommended by the Chairman, President and Chief Executive Officer of MGP, subject to review and approval of the compensation committee of the MGP board of directors (the "Compensation Committee"). Vesting of all grants outstanding is subject to the satisfaction of certain financial tests. If it is not probable the financial tests for a particular grant will be met, any previously expensed amounts for the grant are reversed and no future expense will be recognized for those grants. Assuming the financial tests are met, grants issued to LTIP participants are expected to cliff vest on January 1st of the third year following issuance of the grants. We expect to settle these grants by delivery of ARLP common units, except for the portion of the grants that will satisfy employee tax withholding obligations of LTIP participants. We account for forfeitures of non-vested LTIP grants as they occur. As provided under the distribution equivalent rights ("DERs") provisions of the LTIP and the terms of the LTIP awards, all non-vested grants include contingent rights to receive quarterly distributions in cash or, at the discretion of the Compensation Committee, phantom units in lieu of cash credited to a bookkeeping account with value equal to the cash distributions we make to unitholders during the vesting period.

A summary of non-vested LTIP grants as of and for the three months ended March 31, 2020 is as follows:

(1)	During the three months ended March 31, 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 grant outstanding including 677,476 restricted units that were granted in 2019 (the "2019 Grants"). During the first quarter of 2020, it was determined that the vesting requirements for the 2019 Grants were not probable of being satisfied.

LTIP expense was $(0.7) million and $2.4 million for the three months ended March 31, 2020 and 2019, respectively. LTIP expense for the three months ended March 31, 2020 includes the reversal of $4.8 million of cumulative previously recognized expense for the 2019 Grants, which were determined to be not probable of vesting, offset in part by related DERs for the 2019 Grants previously recorded to equity and then expensed in the three months ended March 31, 2020. The total obligation associated with the LTIP as of March 31, 2020 was $8.1 million and is included in the partners' capital Limited partners-common unitholders line item in our condensed consolidated balance sheets.

As of March 31, 2020, we had 1,446,417 restricted units that are expected to vest, with a weighted average grant date fair value of $13.33 per unit and an intrinsic value of $4.5 million. There was $11.2 million in total unrecognized compensation expense related to the non-vested LTIP grants that are expected to vest. That expense is expected to be recognized over a weighted-average period of 2.1 years.

After consideration of the January 1, 2020 vesting and subsequent issuance of 279,622 common units, approximately 1.0 million units remain available under the LTIP for issuance in the future. This available issuance excludes all grants currently outstanding. Adding back the 2019 Grants that are not probable to vest, approximately 1.7 million units remain available under the LTIP for issuance in the future.

Supplemental Executive Retirement Plan and Directors' Deferred Compensation Plan

We utilize the SERP to provide deferred compensation benefits for certain officers and key employees. All allocations made to participants under the SERP are made in the form of "phantom" ARLP units and SERP distributions will be settled in the form of ARLP common units. The SERP is administered by the Compensation Committee.

Our directors participate in the Directors' Deferred Compensation Plan. Pursuant to the Directors' Deferred Compensation Plan, for amounts deferred either automatically or at the election of the director, a notional account is established and credited with notional common units of ARLP, described in the Directors' Deferred Compensation Plan as "phantom" units. Distributions from the Directors' Deferred Compensation Plan will be settled in the form of ARLP common units.

For both the SERP and Directors' Deferred Compensation Plan, when quarterly cash distributions are made with respect to ARLP common units, an amount equal to such quarterly distribution is credited to each participant's notional account as additional phantom units. All grants of phantom units under the SERP and Directors' Deferred Compensation Plan vest immediately.

A summary of SERP and Directors' Deferred Compensation Plan activity as of and for the three months ended March 31, 2020 is as follows:


	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 March 31, 2020	660,909		24.69		2,049

Total SERP and Directors' Deferred Compensation Plan expense was $0.3 million and $0.4 million for the three months ended March 31, 2020 and 2019, respectively. As of March 31, 2020, the total obligation associated with the SERP and Directors' Deferred Compensation Plan was $16.3 million and is included in the partners' capital Limited partners-common unitholders line item in our condensed consolidated balance sheets.