TRANSACTIONS WITH AFFILIATES (Notes)	12 Months Ended
TRANSACTIONS WITH AFFILIATES (Notes)	Dec. 31, 2019
Related Party Transactions [Abstract]
TRANSACTIONS WITH AFFILIATES	TRANSACTIONS WITH AFFILIATES Revenues The Company has contracted to provide services including gas gathering, compression, processing, transmission, and NGL transmission, pursuant to acreage dedications provided by Apache, comprising the entire Alpine High acreage. In accordance with the terms of these agreements, the Company receives prescribed fees based on the type and volume of product for which the services are provided. For all of the periods presented, the Company’s only significant customer was Apache. Revenues generated under these agreements are presented on the Company’s statement of consolidated operations as “Midstream services revenue — affiliate.” Revenues earned that have not yet been invoiced to Apache are presented on the Company’s consolidated balance sheet as “Revenue receivables.” Refer to Note 4—Revenue Recognition, for further discussion. Cost and Expenses The Company has no employees, and prior to the Business Combination, the Company had no banking or cash management facilities. As such, the Company has contracted with Apache to receive certain operational, maintenance, and management services. In accordance with the terms of these agreements, the Company incurred operations and maintenance expenses of $8.8 million, $9.1 million, and $4.7 million for the years ended December 31, 2019, 2018, and 2017, respectively. The Company incurred general and administrative expenses of $5.4 million, $6.5 million, and $4.0 million for the years ended December 31, 2019, 2018, and 2017 respectively, including expenses related to the operational services agreement and the COMA as further described below. Further information on the related-party agreements in place during the period is provided below. Operational Services Agreement Prior to the Business Combination, Apache provided operations, maintenance, and management services to Altus Midstream Operating, pursuant to a service agreement (the Services Agreement). In accordance with the terms of the Services Agreement, Apache received a fixed fee per month for its overhead and indirect costs incurred on behalf of Altus Midstream Operating. All costs incurred by Altus Midstream Operating were paid by Apache. Construction, Operations, and Maintenance Agreement At the closing of the Business Combination, the Company entered into the COMA with Apache, which superseded the Services Agreement. Under the terms of the COMA, Apache provides certain services related to the design, development, construction, operation, management, and maintenance of certain gathering, processing, and other midstream assets, on behalf of the Company. In return, the Company paid or will pay fees to Apache of (i) $3.0 million for the period beginning on the execution of the COMA at the closing of the Business Combination through December 31, 2019, (ii) $5.0 million for the period of January 1, 2020 through December 31, 2020, (iii) $7.0 million for the period of January 1, 2021 through December 31, 2021 and (iv) $9.0 million annually thereafter, adjusted based on actual internal overhead and general and administrative costs incurred, until terminated. The annual fee was negotiated as part of the Business Combination to reimburse Apache for indirect costs of performing administrative corporate functions for the Company, including services for information technology, risk management, corporate planning, accounting, cash management, and others. In addition, Apache may be reimbursed for certain internal costs and third-party costs incurred in connection with its role as service provider under the COMA. Costs incurred by Apache directly associated with midstream activity, where substantially all the services are rendered for Altus Midstream, are charged to Altus Midstream on a monthly basis. The COMA stipulates that the Company shall provide reimbursement of amounts owing to Apache attributable to a particular month by no later than the last day of the immediately following month. Unpaid amounts accrue interest until settled. The COMA will continue to be effective until terminated (i) upon the mutual consent of Altus and Apache, (ii) by either of Altus and Apache, at its option, upon 30 days’ prior written notice in the event Apache or an affiliate no longer owns a direct or indirect interest in at least 50 percent of the voting or other equity securities of Altus, or (iii) by Altus if Apache fails to perform any of its covenants or obligations due to willful misconduct of certain key personnel and such failure has a material adverse financial impact on Altus. Lease Agreement Concurrent with the closing of the Business Combination, Altus Midstream entered into an operating lease agreement with Apache (the Lease Agreement) relating to the use of certain office buildings, warehouse, and storage facilities located in Reeves County, Texas. Under the terms of the Lease Agreement, Altus Midstream shall pay to Apache on a monthly basis the sum of (i) a base rental charge of $44,500 and (ii) an amount based on Apache’s estimate of the annual costs it expects to incur in connection with the ownership, operation, repair, and/or maintenance of the facilities. The Company incurred total expenses of $1.1 million and $0.1 million for the years ended December 31, 2019 and 2018, respectively, in relation to the Lease Agreement, which are included within operations and maintenance expenses. Unpaid amounts accrue interest until settled. The initial term of the Lease Agreement is four years and may be extended by Altus Midstream for three additional, consecutive periods of twenty-four months. Capitalized Interest Prior to the Business Combination, the Company’s operations were funded entirely by contributions from Apache. Accordingly, Apache allocated a portion of interest on its corporate debt in determining capitalized interest associated with the development of Altus Midstream Operating. Commensurate with Apache’s calculation, interest is capitalized as part of the historical cost of developing and constructing assets. Significant midstream development assets that have not commenced operations qualify for interest capitalization. The associated capitalized interest was determined by multiplying Apache’s weighted-average borrowing cost of debt by the average amount of qualifying midstream assets. The amount of interest allocated and capitalized were $8.2 million and $7.1 million for the years ended December 31, 2018 and 2017, respectively. Management believes the methods used to allocate such expenses incurred by Apache on behalf of the Company are reasonable. Following the closing of the Business Combination, capitalized interest is determined based on interest expense incurred by Altus Midstream. Refer to Note 6—Debt and Financing Costs, for further information. Business Combination Agreements Limited Partnership Agreement of Altus Midstream LP In connection with the Business Combination, Altus Midstream Company, Altus Midstream GP, Altus Midstream LP, and Apache entered into an amended and restated limited partnership agreement of Altus Midstream LP, which was further amended in connection with the subsequent issuance of Preferred Units. The Amended LPA sets forth, among other things, the rights and obligations of (i) Altus Midstream GP as general partner and (ii) Altus Midstream Company, Apache, and Preferred Unit holders as limited partners of Altus Midstream LP. Altus Midstream GP is not entitled to reimbursement for its services as general partner. Refer to Note 1—Summary of Significant Accounting Policies, Note 2—Recapitalization Transaction, and Note 12—Series A Cumulative Redeemable Preferred Units, for further information. Purchase Rights and Restrictive Covenants Agreement At the closing of the Business Combination, the Company entered into a purchase rights and restrictive covenants agreement (the Purchase Rights and Restrictive Covenants Agreement) with Apache. Under the Purchase Rights and Restrictive Covenants Agreement, until the later of the five-year anniversary of the Closing and the date on which Apache and its affiliates cease to own a majority of the Company’s voting common stock, Apache is obligated to provide (i) the first right to pursue any opportunity (including any expansion opportunities) of Apache to acquire or invest, directly or indirectly (including equity investments), in any midstream assets or participate in any midstream opportunities located, in whole or part, within an area covering approximately 1.7 million acres in Reeves, Pecos, Brewster, Culberson, and Jeff Davis Counties in Texas, and (ii) a right of first offer on certain retained midstream assets of Apache. Transactions Prior to the Business Combination Prior to the Business Combination, the Company engaged in certain transactions with Kayne Anderson Sponsor LLC, a Delaware limited liability company (the Sponsor). The Sponsor is a related party as during the periods presented, it owned more than 10 percent of the voting interests of the entity, resulting from the purchase of the Company’s entire share capital upon incorporation in December 2016. The nature of the majority of these transactions is associated with the Company’s incorporation, public offering and Business Combination, as further described in Note 11—Equity. Other transactions with the Sponsor during the periods presented relate to a loan from the Sponsor and a separate administrative services agreement. Loan from the Sponsor On March 21, 2018, the Sponsor agreed to loan up to $0.5 million, as needed, to fund working capital needs pursuant to a promissory note. On August 24, 2018, the Company’s Sponsor agreed to increase such loan up to $1.0 million. These loans were non-interest bearing, and at the closing of the Business Combination the outstanding borrowings totaling $0.7 million were repaid in full. Administrative Services Agreement Beginning April 2017, the Company agreed to pay an affiliate of the Sponsor a total of $5,000 per month for office space, utilities, and secretarial and administrative support. Effective January 1, 2018, the Sponsor’s affiliate agreed to waive the monthly fee until the termination of the agreement. The agreement was terminated at the closing of the Business Combination.