Trust Investments (Amount Of Available-For-Sale Debt Securities By Maturity Periods) (Detail) $ in Millions	Jun. 30, 2024 USD ($)
Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Total Available-for-Sale Debt Securities	$ 1,239
Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Total Available-for-Sale Debt Securities	153
Debt Securities [Member] | Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Less than one year	22
1 - 5 years	330
6 - 10 years	228
11 - 15 years	67
16 - 20 years	103
Over 20 years	489
Debt Securities [Member] | Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Less than one year	7
1 - 5 years	27
6 - 10 years	18
11 - 15 years	9
16 - 20 years	17
Over 20 years	$ 75