Trust Investments (Fair Values And Gross Unrealized Gains And Losses For The Securities) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023		Dec. 31, 2022
Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Cost	$ 2,219		$ 2,130
Gross Unrealized Gains	428		301
Gross Unrealized Losses	124		203
Fair Value	2,523	[1]	2,228	[2]
Nuclear Decommissioning Trust (NDT) Fund [Member] | Domestic Equity Securities [Member]
Schedule of Trust Investments [Line Items]
Cost	482		476
Equity Securities, FV-NI, Unrealized Gain	300		232
Gross Unrealized Losses	(2)		(12)
Fair Value	780		696
Nuclear Decommissioning Trust (NDT) Fund [Member] | International Equity Securities [Member]
Schedule of Trust Investments [Line Items]
Cost	423		336
Equity Securities, FV-NI, Unrealized Gain	118		68
Gross Unrealized Losses	(11)		(28)
Fair Value	530		376
Nuclear Decommissioning Trust (NDT) Fund [Member] | Equity Securities [Member]
Schedule of Trust Investments [Line Items]
Cost	905		812
Equity Securities, FV-NI, Unrealized Gain	418		300
Gross Unrealized Losses	(13)		(40)
Fair Value	1,310		1,072
Unrealized Gains (Losses) on Equity Securities still held	166
Nuclear Decommissioning Trust (NDT) Fund [Member] | Government Obligations [Member]
Schedule of Trust Investments [Line Items]
Cost	759		721
Gross Unrealized Gains	4		0
Gross Unrealized Losses	(72)		(94)
Fair Value	691		627
Nuclear Decommissioning Trust (NDT) Fund [Member] | Corporate Debt Securities [Member]
Schedule of Trust Investments [Line Items]
Cost	555		597
Gross Unrealized Gains	6		1
Gross Unrealized Losses	(39)		(69)
Fair Value	522		529
Nuclear Decommissioning Trust (NDT) Fund [Member] | Debt Securities [Member]
Schedule of Trust Investments [Line Items]
Cost	1,314		1,318
Gross Unrealized Gains	10		1
Gross Unrealized Losses	(111)		(163)
Fair Value	1,213		1,156
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent	(59)
Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Cost	200		213
Gross Unrealized Gains	8		6
Gross Unrealized Losses	29		36
Fair Value	179		183
Rabbi Trust [Member] | Domestic Equity Securities [Member]
Schedule of Trust Investments [Line Items]
Cost	10		14
Equity Securities, FV-NI, Unrealized Gain	8		6
Gross Unrealized Losses	0		0
Fair Value	18		20
Rabbi Trust [Member] | Equity Securities [Member]
Schedule of Trust Investments [Line Items]
Unrealized Gains (Losses) on Equity Securities still held	2
Rabbi Trust [Member] | Government Obligations [Member]
Schedule of Trust Investments [Line Items]
Cost	110		110
Gross Unrealized Gains	0		0
Gross Unrealized Losses	(19)		(21)
Fair Value	91		89
Rabbi Trust [Member] | Corporate Debt Securities [Member]
Schedule of Trust Investments [Line Items]
Cost	80		89
Gross Unrealized Gains	0		0
Gross Unrealized Losses	(10)		(15)
Fair Value	70		74
Rabbi Trust [Member] | Debt Securities [Member]
Schedule of Trust Investments [Line Items]
Cost	190		199
Gross Unrealized Gains	0		0
Gross Unrealized Losses	(29)		(36)
Fair Value	161		$ 163
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent	$ (21)

[1] The NDT Fund Investments table excludes cash and foreign currency of $1 million as of December 31, 2023,         which is part of the NDT Fund.

[2] The NDT Fund Investments table excludes cash and foreign currency of $2 million as of December 31, 2022, which is part of the NDT Fund.