Acquisitions - (Acquisition Narrative) (Details) - USD ($)			4 Months Ended	12 Months Ended
	Dec. 31, 2021	Sep. 01, 2021	Dec. 31, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Nov. 30, 2021
Business Acquisition [Line Items]
Cash consideration				$ 0	$ 0	$ 1,642,000,000
Long-term debt				3,947,000,000	$ 4,392,000,000
Obligation under transportation agreements				9,346,000,000
Indigo Agreement
Business Acquisition [Line Items]
Obligation under transportation agreements		$ 34,000,000		24,000,000
Liability for the estimated future payments		17,000,000		14,000,000
Purchase or volume commitments with gathering fresh water
Business Acquisition [Line Items]
Obligation under transportation agreements		$ 81,000,000		$ 3,000,000
5.375% Senior Notes due February 2029 | Senior Notes
Business Acquisition [Line Items]
Stated interest rate		5.375%		5.375%	5.375%
Long-term debt		$ 700,000,000					$ 700,000,000
8.375% Senior Notes due September 2028 | Senior Notes
Business Acquisition [Line Items]
Stated interest rate				8.375%	8.375%
GEPH Merger
Business Acquisition [Line Items]
Cash consideration	$ 1,263,000,000
Shares of Southwestern common stock issued in respect of outstanding common stock and stock-based awards (in shares)	99,337,748
Business acquisition, equity interest issued or issuable, value assigned	$ 463,000,000		$ 463,000,000			$ 463,000,000
NYSE closing price per share of Southwestern common shares (in dollars per share)	$ 4.66		$ 4.66			$ 4.66
Revolving credit facility	$ 81,000,000		$ 81,000,000			$ 81,000,000
Evaluated oil and gas properties	1,783,000,000		1,783,000,000			1,783,000,000
Unevaluated oil and gas properties	59,000,000		59,000,000			59,000,000
Other property, plant and equipment	$ 2,000,000		2,000,000			2,000,000
Operating revenues acquired through the merger						0
Operating income acquired through the merger						$ 0
Indigo Merger
Business Acquisition [Line Items]
Cash consideration		$ 373,000,000
Shares of Southwestern common stock issued in respect of outstanding common stock and stock-based awards (in shares)		337,827,171
Business acquisition, equity interest issued or issuable, value assigned		$ 1,588,000,000
NYSE closing price per share of Southwestern common shares (in dollars per share)		$ 4.70
Revolving credit facility		$ 95,000,000
Evaluated oil and gas properties		2,724,000,000
Unevaluated oil and gas properties		690,000,000
Other property, plant and equipment		4,000,000
Operating revenues acquired through the merger			682,000,000
Operating income acquired through the merger			$ 472,000,000
Senior unsecured notes		726,000,000
Indigo Merger | 5.375% Senior Notes due February 2029 | Senior Notes
Business Acquisition [Line Items]
Senior note assumed in merger agreement		$ 700,000,000
Stated interest rate		5.375%