| Document and Entity Information | Nov. 03, 2021 |
| Cover [Abstract] | |
| Entity Registrant Name | SOUTHWESTERN ENERGY CO |
| Amendment Flag | true |
| Entity Central Index Key | 0000007332 |
| Document Type | 8-K/A |
| Document Period End Date | Nov. 3, 2021 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-08246 |
| 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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, Par Value $0.01 |
| Trading Symbol | SWN |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Amendment Description | This Amendment No. 1 on Form 8-K/A amends the Current Report on Form 8-K of Southwestern Energy Company, filed on November 5, 2021, in order to file exhibits 99.1 and 99.2, which were unintentionally omitted from the original filing. In addition, Item 1.01 of the original filing has been updated to include the filing of Exhibits 99.1 and 99.2 as exhibits on Form 8-K and not as exhibits to the Merger Agreement (as defined below). No other changes have been made to the original filing other than with respect of the foregoing. |
