SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	6 Months Ended
Jun. 30, 2020
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The consolidated financial results of Altus Midstream are included in the Company’s consolidated financial statements due to the Company’s 100 percent ownership interest in Altus Midstream GP, and Altus Midstream GP’s control of Altus Midstream. The Company has no independent operations or material assets other than its partnership interests in Altus Midstream, which constitutes all of its business. Additionally, the Company’s balance sheet reflects the presentation of noncontrolling interest ownership attributable to the limited partner interests in Altus Midstream held by Apache and the Series A Cumulative Redeemable Preferred Units holders (the Preferred Units). Refer to Note 9—Equity and Note 10—Series A Cumulative Redeemable Preferred Units for further information.
Variable Interest Entity	Variable Interest Entity Altus Midstream is a variable interest entity (VIE) because the partners in Altus Midstream with equity at risk lack the power, through voting or similar rights, to direct the activities that most significantly impact Altus Midstream’s economic performance. A reporting entity that concludes it has a variable interest in a VIE must evaluate whether it has a controlling financial interest in the VIE, such that it is the VIE’s primary beneficiary and should consolidate. The Company is the primary beneficiary of Altus Midstream, and therefore should consolidate Altus Midstream because (i) the Company has the ability to direct the activities of Altus Midstream that most significantly affect its economic performance, and (ii) the Company has the right to receive benefits or the obligation to absorb losses that could be potentially significant to Altus Midstream.
Redeemable Noncontrolling Interest — Apache Limited Partner	Redeemable Noncontrolling Interest — Preferred Unit Limited Partners On June 12, 2019, Altus Midstream issued and sold the Preferred Units in a private offering, and the purchasers of the Preferred Units were admitted as limited partners of Altus Midstream. The Preferred Units will be exchangeable for shares of the Company’s Class A Common Stock at the option of the Preferred Unit holders after the seventh anniversary of Closing or upon the occurrence of specified events, unless otherwise redeemed by Altus Midstream. The Preferred Units are accounted for on the Company’s consolidated balance sheets as a redeemable noncontrolling interest classified as temporary equity based on the terms of the Preferred Units. Certain redemption features embedded within the terms of the Preferred Units require bifurcation and measurement at fair value and are accounted for on the Company’s consolidated balance sheet as a long-term liability embedded derivative. Redeemable Noncontrolling Interest — Apache Limited Partner The Company’s redeemable noncontrolling interest presented in the consolidated financial statements consists of Common Units representing limited partner interests in Altus Midstream held by Apache. Pursuant to certain provisions of the partnership agreement of Altus Midstream (as amended in connection with the Business Combination, and subsequent issuance of Preferred Units, the Amended LPA), the limited partner interests held by Apache are equal to the number of shares of the Company’s Class C common stock, $0.0001 par value (Class C Common Stock), held by Apache. The Company initially recorded the redeemable noncontrolling interest upon the issuance of the Common Units to Apache as part of the Business Combination and based on the recapitalization value ascribed at the Closing Date to the limited partner interest. All or a portion of these Common Units may be redeemed at Apache’s option. The Company has the ability to settle the redemption option either (i) in shares of Class A common stock, $0.0001 par value (Class A Common Stock), on a one-for-one basis or (ii) in cash (based on the fair market value of the Class A Common Stock as determined pursuant to the Contribution Agreement), subject to customary conversion rate adjustments for stock splits, stock dividends, and reclassifications. Upon the future redemption or exchange of Common Units held by Apache, a corresponding number of shares of Class C Common Stock will be cancelled. The Company’s policy is to record the redeemable noncontrolling interest represented by the Common Units held by Apache at the higher of (i) its initial fair value plus accumulated earnings/losses associated with the noncontrolling interest or (ii) the redemption value as of the balance sheet date.
Equity Method Interests	Equity Method Interests The Company follows the equity method of accounting when it does not exercise control over its equity interests, but can exercise significant influence over the operating and financial policies of the entity. Under this method, the equity interests are carried originally at acquisition cost, increased by Altus’ proportionate share of the equity interest’s net income and contributions made by Altus, and decreased by Altus’ proportionate share of the equity interest’s net losses and distributions received by Altus.
Use of Estimates	Use of Estimates Preparation of financial statements in conformity with GAAP and disclosure of contingent assets and liabilities requires management to make estimates and assumptions that affect reported amounts of assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. The Company bases its estimates on historical experience and various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about carrying values of assets and liabilities that are not readily apparent from other sources. The Company evaluates its estimates and assumptions on a regular basis. Actual results may differ from these estimates and assumptions used in preparation of its financial statements, and changes in these estimates are recorded when known.
Fair Value Measurements	Fair Value Measurements Accounting Standards Codification (ASC) 820-10-35, “Fair Value Measurement” (ASC 820), provides a hierarchy that prioritizes and defines the types of inputs used to measure fair value. The fair value hierarchy gives the highest priority to Level 1 inputs, which consist of unadjusted quoted prices for identical instruments in active markets. Level 2 inputs consist of quoted prices for similar instruments. Level 3 valuations are derived from inputs that are significant and unobservable; hence, these valuations have the lowest priority. The valuation techniques that may be used to measure fair value include a market approach, an income approach and a cost approach. A market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets or liabilities. An income approach uses valuation techniques to convert future amounts to a single present amount based on current market expectations, including present value techniques, option-pricing models, and the excess earnings method. The cost approach is based on the amount that currently would be required to replace the service capacity of an asset (replacement cost). Embedded features identified within the Company’s agreements are bifurcated and measured at fair value at the end of each period on the Company’s consolidated balance sheet. Such recurring fair value measurements are presented in further detail in Note 13—Fair Value Measurements. The Company also uses fair value measurements on a nonrecurring basis when certain qualitative assessments of its assets indicate a potential impairment.
Accounts Receivable From/Payable To Apache	Accounts Receivable From/Payable To Apache The accounts receivable from or payable to Apache represent the net result of Altus Midstream’s monthly revenue, capital and operating expenditures, and other miscellaneous transactions to be settled with Apache as provided under the COMA between the two entities. Generally, cash in this amount will be transferred to or from Apache in the month after the Company’s transactions are processed and the net results of operations are determined. However, from time to time, the Company may estimate and transfer the cash settlement amount in the month the transactions are processed, in order to minimize related-party working capital balances.
Revenue recognition	The Company generates revenue from its contracts with customers for the gathering, compression, processing, and transmission of natural gas and NGLs in exchange for a fee per unit of volumes processed during a given month. For all periods presented, revenues with affiliates recorded on the Company’s consolidated statement of operations were attributable to services performed by Altus Midstream for Apache pursuant to separate long-term commercial midstream agreements comprising acreage dedications in Apache’s entire Alpine High resource play. As part of these agreements, substantially all of Apache’s natural gas production from its existing and future owned or controlled properties within the dedicated area is provided to the Company, so long as Apache has the right to market such product. There are no provisions for minimum volume commitments under the existing agreements, and the Company does not own or take title to the volumes it services under these agreements. Altus Midstream, in return for its performance, receives a fee per unit of natural gas or NGLs received during a given month. The service fee charged per unit is set forth for each contract year, subject to yearly fee escalation recalculations. Providing the related service on each volumetric unit represents a single, distinct performance obligation that is satisfied over time as services are rendered. As the amount of volumes serviced are not subject to minimum commitments and each midstream service agreement contains provisions for fee recalculations, substantially all of the transaction price is variable at inception of each contract term. Revenue is measured using the output method based on the amount of volumes serviced each month and the applicable service fee and recognized over time in the amount to which Altus Midstream has the right to invoice, as performance completed to date corresponds directly with the value to its customers. The transaction price is not constrained as variability is resolved prior to the recognition of revenue. Payment under the midstream service agreements are due the month immediately following the month of service. Amounts settled with Apache each month are based on the net amount owed to Altus Midstream or owed to Apache. Revenue receivables from the Company’s contracts with Apache totaled $13.6 million and $15.5 million as of June 30, 2020 and December 31, 2019, respectively, as presented on the Company’s consolidated balance sheet. In accordance with the provisions of ASC Topic 606, “Revenue from Contracts with Customers,” a variable transaction price for each short-term sale is allocated to each performance obligation as the terms of payment relate specifically to the Company’s efforts to satisfy its obligations. As such, the Company has elected the practical expedients available under the standard to not disclose the aggregate transaction price allocated to unsatisfied, or partially unsatisfied, performance obligations as of the end of the reporting period.
Recently Adopted Accounting Standards	Recently Adopted Accounting Standards In June 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2016-13, “Financial Instruments-Credit Losses.” The standard changes the impairment model for trade receivables, held-to-maturity debt securities, net investments in leases, loans, and other financial assets measured at amortized cost. This ASU requires the use of a new forward-looking “expected loss” model compared to the current “incurred loss” model, resulting in accelerated recognition of credit losses. The Company adopted this standard in the first quarter of 2020 with no material impact on its financial statements. In December 2019, the FASB issued ASU 2019-12, “Simplifying the Accounting for Income Taxes.” This pronouncement is part of the Simplification Initiative and simplifies the accounting for income taxes by removing certain exceptions to the general principles of ASC Topic 740 “Income Taxes.” In addition, the amendment improves consistent application of and simplifies GAAP for other areas of ASC Topic 740 by clarifying and amending existing guidance. This update is effective for the Company beginning in the first quarter of 2021, with early adoption permitted. The Company early adopted this standard in the first quarter of 2020 with no material impact on its financial statements.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)

6 Months Ended

Jun. 30, 2020

The consolidated financial results of Altus Midstream are included in the Company’s consolidated financial statements due to the Company’s 100 percent ownership interest in Altus Midstream GP, and Altus Midstream GP’s control of Altus Midstream.

The Company has no independent operations or material assets other than its partnership interests in Altus Midstream, which constitutes all of its business. Additionally, the Company’s balance sheet reflects the presentation of noncontrolling interest ownership attributable to the limited partner interests in Altus Midstream held by Apache and the Series A Cumulative Redeemable Preferred Units holders (the Preferred Units). Refer to Note 9—Equity and Note 10—Series A Cumulative Redeemable Preferred Units for further information.

Variable Interest Entity

Altus Midstream is a variable interest entity (VIE) because the partners in Altus Midstream with equity at risk lack the power, through voting or similar rights, to direct the activities that most significantly impact Altus Midstream’s economic performance.

A reporting entity that concludes it has a variable interest in a VIE must evaluate whether it has a controlling financial interest in the VIE, such that it is the VIE’s primary beneficiary and should consolidate. The Company is the primary beneficiary of Altus Midstream, and therefore should consolidate Altus Midstream because (i) the Company has the ability to direct the activities of Altus Midstream that most significantly affect its economic performance, and (ii) the Company has the right to receive benefits or the obligation to absorb losses that could be potentially significant to Altus Midstream.

Redeemable Noncontrolling Interest — Apache Limited Partner

Redeemable Noncontrolling Interest — Preferred Unit Limited Partners

On June 12, 2019, Altus Midstream issued and sold the Preferred Units in a private offering, and the purchasers of the Preferred Units were admitted as limited partners of Altus Midstream. The Preferred Units will be exchangeable for shares of the Company’s Class A Common Stock at the option of the Preferred Unit holders after the seventh anniversary of Closing or upon the occurrence of specified events, unless otherwise redeemed by Altus Midstream.

The Preferred Units are accounted for on the Company’s consolidated balance sheets as a redeemable noncontrolling interest classified as temporary equity based on the terms of the Preferred Units. Certain redemption features embedded within the terms of the Preferred Units require bifurcation and measurement at fair value and are accounted for on the Company’s consolidated balance sheet as a long-term liability embedded derivative.

Redeemable Noncontrolling Interest — Apache Limited Partner

The Company’s redeemable noncontrolling interest presented in the consolidated financial statements consists of Common Units representing limited partner interests in Altus Midstream held by Apache. Pursuant to certain provisions of the partnership agreement of Altus Midstream (as amended in connection with the Business Combination, and subsequent issuance of Preferred Units, the Amended LPA), the limited partner interests held by Apache are equal to the number of shares of the Company’s Class C common stock, $0.0001 par value (Class C Common Stock), held by Apache.

The Company initially recorded the redeemable noncontrolling interest upon the issuance of the Common Units to Apache as part of the Business Combination and based on the recapitalization value ascribed at the Closing Date to the limited partner interest. All or a portion of these Common Units may be redeemed at Apache’s option. The Company has the ability to settle the redemption option either (i) in shares of Class A common stock, $0.0001 par value (Class A Common Stock), on a one-for-one basis or (ii) in cash (based on the fair market value of the Class A Common Stock as determined pursuant to the Contribution Agreement), subject to customary conversion rate adjustments for stock splits, stock dividends, and reclassifications. Upon the future redemption or exchange of Common Units held by Apache, a corresponding number of shares of Class C Common Stock will be cancelled.

The Company’s policy is to record the redeemable noncontrolling interest represented by the Common Units held by Apache at the higher of (i) its initial fair value plus accumulated earnings/losses associated with the noncontrolling interest or (ii) the redemption value as of the balance sheet date.

Equity Method Interests

The Company follows the equity method of accounting when it does not exercise control over its equity interests, but can exercise significant influence over the operating and financial policies of the entity. Under this method, the equity interests are carried originally at acquisition cost, increased by Altus’ proportionate share of the equity interest’s net income and contributions made by Altus, and decreased by Altus’ proportionate share of the equity interest’s net losses and distributions received by Altus.

Use of Estimates

Preparation of financial statements in conformity with GAAP and disclosure of contingent assets and liabilities requires management to make estimates and assumptions that affect reported amounts of assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. The Company bases its estimates on historical experience and various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about carrying values of assets and liabilities that are not readily apparent from other sources. The Company evaluates its estimates and assumptions on a regular basis. Actual results may differ from these estimates and assumptions used in preparation of its financial statements, and changes in these estimates are recorded when known.

Fair Value Measurements

Accounting Standards Codification (ASC) 820-10-35, “Fair Value Measurement” (ASC 820), provides a hierarchy that prioritizes and defines the types of inputs used to measure fair value. The fair value hierarchy gives the highest priority to Level 1 inputs, which consist of unadjusted quoted prices for identical instruments in active markets. Level 2 inputs consist of quoted prices for similar instruments. Level 3 valuations are derived from inputs that are significant and unobservable; hence, these valuations have the lowest priority.

The valuation techniques that may be used to measure fair value include a market approach, an income approach and a cost approach. A market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets or liabilities. An income approach uses valuation techniques to convert future amounts to a single present amount based on current market expectations, including present value techniques, option-pricing models, and the excess earnings method. The cost approach is based on the amount that currently would be required to replace the service capacity of an asset (replacement cost).

Embedded features identified within the Company’s agreements are bifurcated and measured at fair value at the end of each period on the Company’s consolidated balance sheet. Such recurring fair value measurements are presented in further detail in Note 13—Fair Value Measurements. The Company also uses fair value measurements on a nonrecurring basis when certain qualitative assessments of its assets indicate a potential impairment.

Accounts Receivable From/Payable To Apache

The accounts receivable from or payable to Apache represent the net result of Altus Midstream’s monthly revenue, capital and operating expenditures, and other miscellaneous transactions to be settled with Apache as provided under the COMA between the two entities. Generally, cash in this amount will be transferred to or from Apache in the month after the Company’s transactions are processed and the net results of operations are determined. However, from time to time, the Company may estimate and transfer the cash settlement amount in the month the transactions are processed, in order to minimize related-party working capital balances.

Revenue recognition

The Company generates revenue from its contracts with customers for the gathering, compression, processing, and transmission of natural gas and NGLs in exchange for a fee per unit of volumes processed during a given month. For all periods presented, revenues with affiliates recorded on the Company’s consolidated statement of operations were attributable to services performed by Altus Midstream for Apache pursuant to separate long-term commercial midstream agreements comprising acreage dedications in Apache’s entire Alpine High resource play.

As part of these agreements, substantially all of Apache’s natural gas production from its existing and future owned or controlled properties within the dedicated area is provided to the Company, so long as Apache has the right to market such product. There are no provisions for minimum volume commitments under the existing agreements, and the Company does not own or take title to the volumes it services under these agreements. Altus Midstream, in return for its performance, receives a fee per unit of natural gas or NGLs received during a given month. The service fee charged per unit is set forth for each contract year, subject to yearly fee escalation recalculations.

Providing the related service on each volumetric unit represents a single, distinct performance obligation that is satisfied over time as services are rendered. As the amount of volumes serviced are not subject to minimum commitments and each midstream service agreement contains provisions for fee recalculations, substantially all of the transaction price is variable at inception of each contract term. Revenue is measured using the output method based on the amount of volumes serviced each month and the applicable service fee and recognized over time in the amount to which Altus Midstream has the right to invoice, as performance completed to date corresponds directly with the value to its customers. The transaction price is not constrained as variability is resolved prior to the recognition of revenue.

Payment under the midstream service agreements are due the month immediately following the month of service. Amounts settled with Apache each month are based on the net amount owed to Altus Midstream or owed to Apache. Revenue receivables from the Company’s contracts with Apache totaled $13.6 million and $15.5 million as of June 30, 2020 and December 31, 2019, respectively, as presented on the Company’s consolidated balance sheet.

In accordance with the provisions of ASC Topic 606, “Revenue from Contracts with Customers,” a variable transaction price for each short-term sale is allocated to each performance obligation as the terms of payment relate specifically to the Company’s efforts to satisfy its obligations. As such, the Company has elected the practical expedients available under the standard to not disclose the aggregate transaction price allocated to unsatisfied, or partially unsatisfied, performance obligations as of the end of the reporting period.

Recently Adopted Accounting Standards

In June 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2016-13, “Financial Instruments-Credit Losses.” The standard changes the impairment model for trade receivables, held-to-maturity debt securities, net investments in leases, loans, and other financial assets measured at amortized cost. This ASU requires the use of a new forward-looking “expected loss” model compared to the current “incurred loss” model, resulting in accelerated recognition of credit losses. The Company adopted this standard in the first quarter of 2020 with no material impact on its financial statements.

In December 2019, the FASB issued ASU 2019-12, “Simplifying the Accounting for Income Taxes.” This pronouncement is part of the Simplification Initiative and simplifies the accounting for income taxes by removing certain exceptions to the general principles of ASC Topic 740 “Income Taxes.” In addition, the amendment improves consistent application of and simplifies GAAP for other areas of ASC Topic 740 by clarifying and amending existing guidance. This update is effective for the Company beginning in the first quarter of 2021, with early adoption permitted. The Company early adopted this standard in the first quarter of 2020 with no material impact on its financial statements.