Acquisitions - (Acquisition Narrative) (Details) - USD ($)				1 Months Ended	2 Months Ended	4 Months Ended	12 Months Ended
	Dec. 31, 2021	Sep. 01, 2021	Nov. 13, 2020	Aug. 31, 2020	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Nov. 30, 2021
Business Acquisition [Line Items]
Cash consideration							$ 0	$ 1,642,000,000	$ 0
Long-term debt	$ 5,407,000,000					$ 5,407,000,000	4,392,000,000	$ 5,407,000,000
Obligation under transportation agreements							$ 10,414,000,000
Minimum
Business Acquisition [Line Items]
Contractual commitments payments, term (in years)							7 months
Indigo Agreement
Business Acquisition [Line Items]
Obligation under transportation agreements		$ 34,000,000					$ 30,000,000
Liability for the estimated future payments		17,000,000					16,000,000
Purchase or volume commitments with gathering fresh water
Business Acquisition [Line Items]
Obligation under transportation agreements		$ 81,000,000					$ 26,000,000
5.375% Senior Notes due February 2029 | Senior Notes
Business Acquisition [Line Items]
Stated interest rate	5.375%	5.375%				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%	8.375%	8.375%
Senior notes, noncurrent				$ 350,000,000
Eight Point Eight Seven Five Percent Senior Notes Due 2023 | Senior Notes | Montage Merger
Business Acquisition [Line Items]
Stated interest rate				8.875%
Senior notes, noncurrent				$ 510,000,000
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
Offering price (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
Offering price (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%
Montage Merger
Business Acquisition [Line Items]
Shares of Southwestern common stock issued in respect of outstanding common stock and stock-based awards (in shares)			69,740,848
Business acquisition, equity interest issued or issuable, value assigned			$ 213,000,000
Offering price (in dollars per share)			$ 3.05	$ 2.50
Operating revenues acquired through the merger					$ 63,000,000
Operating income acquired through the merger					$ 28,000,000
Montage Merger | Public Stock Offering
Business Acquisition [Line Items]
Underwritten public offering of common stock (in shares)				63,250,000
Net proceeds from public offering				$ 152,000,000
Montage Merger | 8.375% Senior Notes due September 2028 | Senior Notes
Business Acquisition [Line Items]
Stated interest rate				8.375%
Senior notes, noncurrent				$ 350,000,000