Earnings Per Share (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended		9 Months Ended
	Dec. 31, 2021	Sep. 01, 2021	Sep. 30, 2022	Jun. 30, 2022	Sep. 30, 2022
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Treasury stock acquired (in shares)			10,800,000		13,600,000
Treasury stock acquired, average cost per share (in dollars per share)			$ 7.41		$ 7.35
Treasury stock			$ (80)	$ (20)	$ (100)
GEPH Merger
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Shares of Southwestern common stock issued (in shares)	99,337,748
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable	$ 463
NYSE closing price per share of Southwestern common shares (in dollars per share)	$ 4.66
Indigo Natural Resources, LLC
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Shares of Southwestern common stock issued (in shares)		337,827,171
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable		$ 1,588
NYSE closing price per share of Southwestern common shares (in dollars per share)		$ 4.70