Financial Risk Management Activities (Schedule Of Derivative Transactions Designated And Effective As Cash Flow Hedges) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	$ 18	$ 0	$ 32	$ 0
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion		(1)		(3)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(243)	(10)	(260)	(23)
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion	3		3
Cash Flow Hedges [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	2	(1)	2	(2)	$ (3)
Interest Rate Swap [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	18	0	32	0
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion		$ (1)		$ (3)
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion	$ 3		$ 3