Financial Risk Management Activities (Schedule Of Derivative Transactions Designated And Effective As Cash Flow Hedges) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	$ 2	$ 17	$ 30	$ 14
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion				0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(1)	(7)	(3)	(17)
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion	4	1	7
Cash Flow Hedges [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	3	1	5	0	$ 3
Interest Rate Swap [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	2	17	30	14
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion				$ 0
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion	$ 4	$ 1	$ 7