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Acquisitions and Divestitures - (Schedule of Consideration Paid to Equity Holders of GEPH) (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Dec. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Cash consideration		$ 1,642	$ 0	$ 0
GEPH Merger
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Shares of Southwestern common stock issued in respect of outstanding common stock and stock-based awards (in shares)	99,337,748
Offering price (in dollars per share)	$ 4.66	$ 4.66
Total consideration (fair value of Southwestern common shares issued)	$ 463	$ 463
Cash consideration	1,269
Total consideration	$ 1,732