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, 2023		Jun. 30, 2023		Dec. 31, 2022
Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Trust Investments, Cost	$ 2,146		$ 2,146		$ 2,130
Gross Unrealized Gains	396		396		301
Gross Unrealized Losses	(161)		(161)		(203)
Trust Investments, Fair Value	2,381	[1]	2,381	[1]	2,228	[2]
NDT Fund Foreign Currency	2		2		2
Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Trust Investments, Cost	209		209		213
Gross Unrealized Gains	8		8		6
Gross Unrealized Losses	(32)		(32)		(36)
Trust Investments, Fair Value	185		185		183
Total Debt Securities [Member] | Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	1,327		1,327		1,318
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	2		2		1
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(137)		(137)		(163)
Debt Securities, Available-for-Sale, Fair Value	1,192		1,192		1,156
Total Debt Securities [Member] | Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	196		196		199
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)		(36)
Debt Securities, Available-for-Sale, Fair Value	164		164		163
Equity Securities [Member] | Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Equity Securities, Cost	819		819		812
Equity Securities, Accumulated Gross Unrealized Gain			394		300
Equity Securities, FV-NI, Unrealized Loss			(24)		(40)
Equity Securities, Fair Value	1,189		1,189		1,072
Unrealized Gains (Losses) on Equity Securities still held	59		114
Equity Securities [Member] | Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Unrealized Gains (Losses) on Equity Securities still held	1		2
Corporate Debt Obligations [Member] | Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	585		585		597
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1		1		1
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(55)		(55)		(69)
Debt Securities, Available-for-Sale, Fair Value	531		531		529
Corporate Debt Obligations [Member] | Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	85		85		89
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	(13)		(13)		(15)
Debt Securities, Available-for-Sale, Fair Value	72		72		74
Government Debt Securities [Member] | Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	742		742		721
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1		1		0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(82)		(82)		(94)
Debt Securities, Available-for-Sale, Fair Value	661		661		627
Government Debt Securities [Member] | Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	111		111		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	(19)		(19)		(21)
Debt Securities, Available-for-Sale, Fair Value	92		92		89
International Equity Securities [Member] | Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Equity Securities, Cost	361		361		336
Equity Securities, Accumulated Gross Unrealized Gain			94		68
Equity Securities, FV-NI, Unrealized Loss			(19)		(28)
Equity Securities, Fair Value	436		436		376
Domestic Equity Securities [Member] | Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Equity Securities, Cost	458		458		476
Equity Securities, Accumulated Gross Unrealized Gain			300		232
Equity Securities, FV-NI, Unrealized Loss			(5)		(12)
Equity Securities, Fair Value	753		753		696
Domestic Equity Securities [Member] | Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Equity Securities, Cost	13		13		14
Equity Securities, Accumulated Gross Unrealized Gain			8		6
Equity Securities, FV-NI, Unrealized Loss			0		0
Equity Securities, Fair Value	$ 21		21		$ 20
Debt Securities [Member] | Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
After tax amount of net unrealized gains recognized in AOCI			(80)
Debt Securities [Member] | Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
After tax amount of net unrealized gains recognized in AOCI			$ (23)

[1] The NDT Fund Investments table excludes cash and foreign currency of $2 million as of June 30, 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.