Equity	9 Months Ended
Equity	Sep. 30, 2019
Equity [Abstract]
EQUITY	EQUITY Stock-based Compensation In February 2019, the Company granted awards to certain of its employees of 428,006 service-based restricted stock units to be settled in cash, which are liability instruments, and 428,006 performance-based stock units, which are equity instruments. The performance-based stock units vest in an amount between zero and 200% of the target units granted based on the Company’s relative total shareholder return over the three-year period ending December 31, 2021, as compared to a designated peer group. The service-based restricted stock units vest ratably over three years, and the performance-based stock units are eligible to vest after completion of the three-year performance period. The fair value of these awards was approximately $16.8 million on the grant date. In April 2019, the Company granted awards to certain of its employees of 259,038 service-based restricted stock units to be settled in cash, which are liability instruments, and 205,361 shares of service-based restricted stock, which are equity instruments. Both the liability instruments and the equity instruments vest ratably over three years. The fair value of these awards was approximately $9.2 million on the grant date. In August 2019, the Company granted awards to certain of its employees of 540,250 stock options that vest ratably over three years. The fair value of these awards was approximately $3.0 million. San Mateo II On February 25, 2019, the Company announced the formation of San Mateo II, a strategic joint venture with a subsidiary of Five Point Energy LLC (“Five Point”) designed to expand the Company’s midstream operations in the Delaware Basin, specifically in Eddy County, New Mexico. San Mateo II is owned 51% by the Company and 49% by Five Point. In addition, Five Point has committed to pay $125 million of the first $150 million of capital expenditures incurred by San Mateo II to develop facilities in the Stebbins area and surrounding leaseholds in the southern portion of the Arrowhead asset area (the “Greater Stebbins Area”) and the Stateline asset area. The Company also has the ability to earn up to $150 million in deferred performance incentives over the next five years related to the formation of San Mateo II, plus additional performance incentives for securing volumes from third-party customers. During the first quarter of 2019, the Company contributed $1.0 million of property to San Mateo II. During the three and nine months ended September 30, 2019, the Company contributed $4.5 million and $6.0 million of cash and Five Point contributed $22.5 million and $34.0 million of cash to San Mateo II, respectively. Performance Incentives In connection with the formation of San Mateo I in 2017, the Company has the ability to earn a total of $73.5 million in performance incentives to be paid by Five Point over a five-year period. The Company earned, and Five Point paid to the Company, $14.7 million in performance incentives during each of the nine months ended September 30, 2019 and 2018, and the Company may earn up to an additional $44.1 million in performance incentives over the next three years. These performance incentives are recorded as an increase to additional paid-in capital when received. These performance incentives for the nine months ended September 30, 2019 and 2018 are also denoted as “Contributions related to formation of San Mateo I” under “Financing activities” in the Company’s interim unaudited condensed consolidated statements of cash flows and changes in shareholders’ equity.