Cover Page - USD ($)	12 Months Ended
Cover Page - USD ($)	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

SOUTHWESTERN ENERGY CO 10-K/A