| Cover Page - USD ($) | 12 Months Ended | | |
| Dec. 31, 2023 | Apr. 29, 2024 | Jun. 30, 2023 |
| Entity Information [Line Items] | | | |
| Document Type | 10-K/A | | |
| Document Annual Report | true | | |
| Document Period End Date | Dec. 31, 2023 | | |
| Current Fiscal Year End Date | --12-31 | | |
| Entity File Number | 001-08246 | | |
| Entity Registrant Name | Southwestern Energy Company | | |
| Amendment Flag | true | | |
| Document Fiscal Year Focus | 2023 | | |
| Document Fiscal Period Focus | FY | | |
| Entity Central Index Key | 0000007332 | | |
| Entity Incorporation, State or Country Code | DE | | |
| Entity Tax Identification Number | 71-0205415 | | |
| Entity Address, Address Line One | 10000 Energy Drive | | |
| Entity Address, City or Town | Spring | | |
| Entity Address, State or Province | TX | | |
| Entity Address, Postal Zip Code | 77389 | | |
| City Area Code | 832 | | |
| Local Phone Number | 796-1000 | | |
| Title of 12(b) Security | Common Stock, Par Value $0.01 | | |
| Trading Symbol | SWN | | |
| Security Exchange Name | NYSE | | |
| Entity Well-known Seasoned Issuer | Yes | | |
| Entity Voluntary Filers | No | | |
| Entity Current Reporting Status | Yes | | |
| Entity Interactive Data Current | Yes | | |
| Entity Filer Category | Large Accelerated Filer | | |
| Entity Small Business | false | | |
| Entity Emerging Growth Company | false | | |
| ICFR Auditor Attestation Flag | true | | |
| Document Financial Statement Error Correction [Flag] | false | | |
| Entity Shell Company | false | | |
| Entity Public Float | | | $ 6,928,429,581 |
| Entity Common Stock, Shares Outstanding | | 1,102,846,071 | |
| Documents Incorporated by Reference [Text Block] | None. | | |
| Amendment Description | This Amendment No. 1 on Form 10-K/A (this “Form 10-K/A”) to the Annual Report on Form 10-K of Southwestern Energy Company (including its subsidiaries, collectively, “we”, “our”, “us”, “the “Company,” or “Southwestern”) for the fiscal year ended December 31, 2023, originally filed with the Securities and Exchange Commission (the “SEC”) on February 22, 2024 (the “Original 10-K”), is being filed pursuant to General Instruction G(3) to Form 10-K to provide the information required by Part III of Form 10-K. This information was previously omitted from the Original 10-K in reliance on General Instruction G(3) to Form 10-K, which permits such information to be filed as an amendment to Form 10-K or incorporated in the Form 10-K by reference from the Company’s definitive proxy statement if such statement is filed no later than 120 days after the Company’s fiscal year-end. We are filing this Form 10-K/A at this time as we no longer intend to file a definitive proxy statement for an annual meeting of shareholders within 120 days of the end of our fiscal year ended December 31, 2023 in light of the Merger (as defined below). In addition, in connection with the filing of this Form 10-K/A and pursuant to the rules of the SEC, we are including with this Form 10-K/A new certifications of our principal executive officer and principal financial officer pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. Item 15 of Part IV has also been amended and restated to reflect the filing of these new certifications. We are not including certifications under Section 906 of Sarbanes-Oxley Act of 2002 as no financial statements are being filed with this Form 10-K/A. As disclosed in our Current Report on Form 8-K filed with the SEC on January 11, 2024, we entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Chesapeake Energy Corporation (“Chesapeake”), Hulk Merger Sub, Inc. and Hulk LLC Sub, LLC, pursuant to which, on the terms and subject to the conditions therein, a subsidiary of Chesapeake will merge with and into the Company, with the Company being the surviving entity and a direct wholly owned subsidiary of Chesapeake (the “Merger”). Except as described above, this Form 10-K/A does not modify or update disclosures in, or exhibits to, the Original 10-K. Furthermore, this Form 10- K/A does not change any previously reported financial results, nor does it reflect events occurring after the date of the Original 10-K. Information not affected by this Form 10-K/A remains unchanged and reflects the disclosures made at the time the Original 10-K was filed. Accordingly, this Form 10-K/A should be read in conjunction with the Original 10-K and with our filings with the SEC subsequent to the filing of the Original 10-K. | | |
| Document Transition Report | false | | |
