Significant Accounting Policies (Policies)	3 Months Ended
Mar. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The DT Midstream Consolidated Financial Statements and Notes to Consolidated Financial Statements are prepared under GAAP. These accounting principles require management to use estimates and assumptions that impact reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities. Actual results may differ from DT Midstream’s estimates. DT Midstream believes the assumptions underlying these financial statements are reasonable. Certain prior-period amounts have been reclassified to conform to current-year presentation. In DT Midstream's opinion, the accompanying unaudited Consolidated Financial Statements include all adjustments, consisting of normal recurring adjustments, necessary to present a fair statement of our financial position as of March 31, 2023, results of operations for the three months ended March 31, 2023 and 2022, statement of changes in stockholders' equity for the three months ended March 31, 2023 and 2022, and cash flows for the three months ended March 31, 2023 and 2022. The balance sheet as of December 31, 2022 was derived from audited annual financial statements but does not include all disclosures required by GAAP. Financial results for this interim period are not necessarily indicative of results that may be expected for any other interim period or for the year ending December 31, 2023. The Consolidated Financial Statements should be read in conjunction with DT Midstream Consolidated Financial Statements and Notes to Consolidated Financial Statements included in DT Midstream's 2022 Annual Report on Form 10-K.
Principles of Consolidation	Principles of Consolidation DT Midstream consolidates all majority-owned subsidiaries and investments in entities in which we have a controlling influence. Non-majority owned investments are accounted for using the equity method of accounting when DT Midstream is able to significantly influence the operating policies of the investee. When DT Midstream does not influence the operating policies of an investee, the equity investment is measured at fair value, if readily determinable, or if not readily determinable, at cost less impairment, if applicable. DT Midstream eliminates all intercompany balances and transactions. DT Midstream evaluates whether an entity is a VIE whenever reconsideration events occur. DT Midstream consolidates VIEs for which we are the primary beneficiary. If DT Midstream is not the primary beneficiary and an ownership interest is held, the VIE is accounted for under the equity method of accounting. When assessing the determination of the primary beneficiary, DT Midstream considers all relevant facts and circumstances, including: the power, through voting or similar rights, to direct the activities of the VIE that most significantly impact the VIE's economic performance and the obligation to absorb the expected losses and/or the right to receive the expected returns of the VIE. DT Midstream performs ongoing reassessments of all VIEs to determine if the primary beneficiary status has changed. DT Midstream owns an 85% interest in the Stonewall Gas Gathering VIE and is the primary beneficiary, therefore Stonewall Gas Gathering is consolidated. DT Midstream owns a 50% interest in the South Romeo VIE and is the primary beneficiary, therefore South Romeo is consolidated.
Cash and Cash Equivalents	Cash and Cash EquivalentsCash and cash equivalents include cash in banks and highly liquid money market investments with remaining maturities of three months or less, when purchased. Cash equivalents are stated at cost, which approximates fair value.
Financing Receivables	Financing Receivables Financing receivables are primarily composed of trade accounts receivable and notes receivable, which are stated at net realizable value. DT Midstream regularly monitors the credit quality of its financing receivables by reviewing counterparty credit quality indicators and monitoring for triggering events, such as a credit rating downgrade or bankruptcy. DT Midstream has three internal grades of credit quality, with internal grade 1 as the lowest risk and internal grade 3 as the highest risk. The related credit quality indicators and risk ratings utilized to develop the internal grades have been updated through March 31, 2023. As of March 31, 2023, the Notes receivable — related party of $4 million, which originated prior to 2021, was classified as internal grade 1. There are no notes receivable on nonaccrual status and no past due financing receivables as of March 31, 2023. For trade accounts receivable, the customer allowance for expected credit loss is calculated based on specific review of future collections based on receivable balances generally in excess of 30 days. Existing and future economic conditions, historical loss rates, customer trends and other relevant factors that may affect our ability to collect are also considered. Receivables are written off on a specific identification basis and determined based on the particular circumstances of the associated receivable.
Recently Issued Pronouncements	Recently Adopted Pronouncements In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848) - Facilitation of the Effects of Reference Rate Reform on Financial Reporting, as amended. Subsequently, in January 2021, the FASB issued ASU No. 2021-01, Reference Rate Reform (Topic 848) - Scope, as amended. The amendments in these updates provide optional expedients and exceptions for applying GAAP to contract modifications and hedging relationships, subject to meeting certain criteria, that reference LIBOR or another reference rate expected to be discontinued. The guidance can be applied prospectively from any date beginning March 12, 2020 through December 31, 2022. Subsequently, in December 2022, the FASB issued ASU No. 2022-06, Deferral of the Sunset Date of Topic 848, which further deferred the sunset date to December 31, 2024. The optional relief is temporary and cannot be applied to contract modifications and hedging relationships entered into or evaluated after December 31, 2024. DT Midstream adopted this standard in 2022, which did not have a material impact on our Consolidated Financial Statements.

Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2023

The DT Midstream Consolidated Financial Statements and Notes to Consolidated Financial Statements are prepared under GAAP. These accounting principles require management to use estimates and assumptions that impact reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities. Actual results may differ from DT Midstream’s estimates. DT Midstream believes the assumptions underlying these financial statements are reasonable. Certain prior-period amounts have been reclassified to conform to current-year presentation.

In DT Midstream's opinion, the accompanying unaudited Consolidated Financial Statements include all adjustments, consisting of normal recurring adjustments, necessary to present a fair statement of our financial position as of March 31, 2023, results of operations for the three months ended March 31, 2023 and 2022, statement of changes in stockholders' equity for the three months ended March 31, 2023 and 2022, and cash flows for the three months ended March 31, 2023 and 2022. The balance sheet as of December 31, 2022 was derived from audited annual financial statements but does not include all disclosures required by GAAP. Financial results for this interim period are not necessarily indicative of results that may be expected for any other interim period or for the year ending December 31, 2023. The Consolidated Financial Statements should be read in conjunction with DT Midstream Consolidated Financial Statements and Notes to Consolidated Financial Statements included in DT Midstream's 2022 Annual Report on Form 10-K.

Principles of Consolidation

DT Midstream consolidates all majority-owned subsidiaries and investments in entities in which we have a controlling influence. Non-majority owned investments are accounted for using the equity method of accounting when DT Midstream is able to significantly influence the operating policies of the investee. When DT Midstream does not influence the operating policies of an investee, the equity investment is measured at fair value, if readily determinable, or if not readily determinable, at cost less impairment, if applicable. DT Midstream eliminates all intercompany balances and transactions.

DT Midstream evaluates whether an entity is a VIE whenever reconsideration events occur. DT Midstream consolidates VIEs for which we are the primary beneficiary. If DT Midstream is not the primary beneficiary and an ownership interest is held, the VIE is accounted for under the equity method of accounting. When assessing the determination of the primary beneficiary, DT Midstream considers all relevant facts and circumstances, including: the power, through voting or similar rights, to direct the activities of the VIE that most significantly impact the VIE's economic performance and the obligation to absorb the expected losses and/or the right to receive the expected returns of the VIE. DT Midstream performs ongoing reassessments of all VIEs to determine if the primary beneficiary status has changed.

DT Midstream owns an 85% interest in the Stonewall Gas Gathering VIE and is the primary beneficiary, therefore Stonewall Gas Gathering is consolidated. DT Midstream owns a 50% interest in the South Romeo VIE and is the primary beneficiary, therefore South Romeo is consolidated.

Cash and Cash Equivalents

Cash and Cash EquivalentsCash and cash equivalents include cash in banks and highly liquid money market investments with remaining maturities of three months or less, when purchased. Cash equivalents are stated at cost, which approximates fair value.

Financing Receivables

Financing receivables are primarily composed of trade accounts receivable and notes receivable, which are stated at net realizable value.

DT Midstream regularly monitors the credit quality of its financing receivables by reviewing counterparty credit quality indicators and monitoring for triggering events, such as a credit rating downgrade or bankruptcy. DT Midstream has three internal grades of credit quality, with internal grade 1 as the lowest risk and internal grade 3 as the highest risk. The related credit quality indicators and risk ratings utilized to develop the internal grades have been updated through March 31, 2023. As of March 31, 2023, the Notes receivable — related party of $4 million, which originated prior to 2021, was classified as internal grade 1. There are no notes receivable on nonaccrual status and no past due financing receivables as of March 31, 2023.

For trade accounts receivable, the customer allowance for expected credit loss is calculated based on specific review of future collections based on receivable balances generally in excess of 30 days. Existing and future economic conditions, historical loss rates, customer trends and other relevant factors that may affect our ability to collect are also considered. Receivables are written off on a specific identification basis and determined based on the particular circumstances of the associated receivable.

Recently Issued Pronouncements

Recently Adopted Pronouncements

In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848) - Facilitation of the Effects of Reference Rate Reform on Financial Reporting, as amended. Subsequently, in January 2021, the FASB issued ASU No. 2021-01, Reference Rate Reform (Topic 848) - Scope, as amended. The amendments in these updates provide optional expedients and exceptions for applying GAAP to contract modifications and hedging relationships, subject to meeting certain criteria, that reference LIBOR or another reference rate expected to be discontinued. The guidance can be applied prospectively from any date beginning March 12, 2020 through December 31, 2022. Subsequently, in December 2022, the FASB issued ASU No. 2022-06, Deferral of the Sunset Date of Topic 848, which further deferred the sunset date to December 31, 2024. The optional relief is temporary and cannot be applied to contract modifications and hedging relationships entered into or evaluated after December 31, 2024. DT Midstream adopted this standard in 2022, which did not have a material impact on our Consolidated Financial Statements.