Trust Investments (Fair Values And Gross Unrealized Gains And Losses For The Securities Held) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2024		Jun. 30, 2024		Dec. 31, 2023
Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Trust Investments, Cost	$ 2,312		$ 2,312		$ 2,219
Gross Unrealized Gains	486		486		428
Gross Unrealized Losses	(147)		(147)		(124)
Trust Investments, Fair Value	2,651	[1]	2,651	[1]	2,523	[2]
NDT Fund Foreign Currency	1		1		1
Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Trust Investments, Cost	194		194		200
Gross Unrealized Gains	9		9		8
Gross Unrealized Losses	(32)		(32)		(29)
Trust Investments, Fair Value	171		171		179
Total Debt Securities [Member] | Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	1,361		1,361		1,314
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	3		3		10
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(125)		(125)		(111)
Debt Securities, Available-for-Sale, Fair Value	1,239		1,239		1,213
Total Debt Securities [Member] | Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	185		185		190
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0		0		0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(32)		(32)		(29)
Debt Securities, Available-for-Sale, Fair Value	153		153		161
Equity Securities [Member] | Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Equity Securities, Cost	951		951		905
Equity Securities, Accumulated Gross Unrealized Gain			483		418
Equity Securities, FV-NI, Unrealized Loss			(22)		(13)
Equity Securities, Fair Value	1,412		1,412		1,310
Unrealized Gains (Losses) on Equity Securities still held	14		88
Equity Securities [Member] | Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Unrealized Gains (Losses) on Equity Securities still held	1		1
Corporate Debt Obligations [Member] | Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	562		562		555
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	2		2		6
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(37)		(37)		(39)
Debt Securities, Available-for-Sale, Fair Value	527		527		522
Corporate Debt Obligations [Member] | Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	77		77		80
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0		0		0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(11)		(11)		(10)
Debt Securities, Available-for-Sale, Fair Value	66		66		70
Government Debt Securities [Member] | Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	799		799		759
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1		1		4
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(88)		(88)		(72)
Debt Securities, Available-for-Sale, Fair Value	712		712		691
Government Debt Securities [Member] | Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	108		108		110
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0		0		0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(21)		(21)		(19)
Debt Securities, Available-for-Sale, Fair Value	87		87		91
International Equity Securities [Member] | Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Equity Securities, Cost	405		405		423
Equity Securities, Accumulated Gross Unrealized Gain			121		118
Equity Securities, FV-NI, Unrealized Loss			(17)		(11)
Equity Securities, Fair Value	509		509		530
Domestic Equity Securities [Member] | Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Equity Securities, Cost	546		546		482
Equity Securities, Accumulated Gross Unrealized Gain			362		300
Equity Securities, FV-NI, Unrealized Loss			(5)		(2)
Equity Securities, Fair Value	903		903		780
Domestic Equity Securities [Member] | Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Equity Securities, Cost	9		9		10
Equity Securities, Accumulated Gross Unrealized Gain			9		8
Equity Securities, FV-NI, Unrealized Loss			0		0
Equity Securities, Fair Value	$ 18		18		$ 18
Debt Securities [Member] | Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
After tax amount of net unrealized gains (losses) recognized in AOCI			(71)
Debt Securities [Member] | Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
After tax amount of net unrealized gains (losses) recognized in AOCI			$ (24)

[1] The NDT Fund Investments table excludes cash and foreign currency of $1 million as of June 30, 2024, which is part of the NDT Fund.

[2] 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.