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Asset Retirement Obligations (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2022
Dec. 31, 2021
Asset retirement obligations    
Balance at beginning of year $ 469 $ 377
Additional liabilities accrued 19 28
Revisions in estimated cash outflows 11 42
Disposition of assets (1) (1)
Accretion expense 26 23
Balance at end of year $ 524 $ 469