Long-Term Incentive Plan

The compensation committee of our general partner’s board of directors administers our long-term incentive plan (“LTIP”) covering certain of our employees and the independent directors of our general partner. The LTIP primarily consists of phantom units and permits the grant of awards covering an aggregate payout of 11.9 million of our limited partner units. The estimated units remaining available under the LTIP at March 31, 2019 total 1.6 million.

Our equity-based incentive compensation expense was as follows (in thousands):



	Three Months Ended March 31,
	2018		2019
Performance-based awards	$	5,924	$	3,644
Time-based awards	708		1,270
Total	$	6,632	$	4,914

Allocation of LTIP expense on our consolidated statements of income:
G&A expense	$	6,577	$	4,871
Operating expense	55		43
Total	$	6,632	$	4,914

On February 1, 2019, 347,473 unit awards were granted pursuant to our LTIP. These awards included both performance-based and time-based awards and have a three-year vesting period that will end on December 31, 2021.

Basic and Diluted Net Income Per Limited Partner Unit

The difference between our actual limited partner units outstanding and our weighted-average number of limited partner units outstanding used to calculate basic net income per unit is due to the impact of: (i) the unit awards issued to non-employee directors and (ii) the weighted average effect of units actually issued during a period. The difference between the weighted-average number of limited partner units outstanding used for basic and diluted net income per unit calculations on our consolidated statements of income is primarily the dilutive effect of unit awards associated with our LTIP that have not yet vested.