Trust Investments (Fair Values And Gross Unrealized Gains And Losses For The Securities Held) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2022		Sep. 30, 2022		Dec. 31, 2021
Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Trust Investments, Cost	$ 2,142		$ 2,142		$ 2,157
Gross Unrealized Gains	250		250		510
Gross Unrealized Losses	(268)		(268)		(32)
Trust Investments, Fair Value	2,124	[1]	2,124	[1]	2,635	[2]
NDT Fund Foreign Currency	1		1		2
Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Trust Investments, Cost	215		215		226
Gross Unrealized Gains	5		5		18
Gross Unrealized Losses	(38)		(38)		(2)
Trust Investments, Fair Value	182		182		242
Total Debt Securities [Member] | Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	1,317		1,317		1,320
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0		0		28
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(182)		(182)		(14)
Debt Securities, Available-for-Sale, Fair Value	1,135		1,135		1,334
Total Debt Securities [Member] | Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	200		200		212
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0		0		6
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(38)		(38)		(2)
Debt Securities, Available-for-Sale, Fair Value	162		162		216
Equity Securities [Member] | Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Equity Securities, Cost	825		825		837
Equity Securities, Accumulated Gross Unrealized Gain			250		482
Equity Securities, FV-NI, Unrealized Loss			(86)		(18)
Equity Securities, Fair Value	989		989		1,301
Unrealized Gains (Losses) on Equity Securities still held	(73)		(268)
Equity Securities [Member] | Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Unrealized Gains (Losses) on Equity Securities still held	(1)		(7)
Corporate Debt Obligations [Member] | Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	614		614		637
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0		0		16
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(81)		(81)		(6)
Debt Securities, Available-for-Sale, Fair Value	533		533		647
Corporate Debt Obligations [Member] | Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	89		89		105
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0		0		5
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(17)		(17)		(1)
Debt Securities, Available-for-Sale, Fair Value	72		72		109
Government Debt Securities [Member] | Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	703		703		683
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0		0		12
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(101)		(101)		(8)
Debt Securities, Available-for-Sale, Fair Value	602		602		687
Government Debt Securities [Member] | Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	111		111		107
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0		0		1
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(21)		(21)		(1)
Debt Securities, Available-for-Sale, Fair Value	90		90		107
International Equity Securities [Member] | Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Equity Securities, Cost	330		330		346
Equity Securities, Accumulated Gross Unrealized Gain			41		119
Equity Securities, FV-NI, Unrealized Loss			(52)		(15)
Equity Securities, Fair Value	319		319		450
Domestic Equity Securities [Member] | Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Equity Securities, Cost	495		495		491
Equity Securities, Accumulated Gross Unrealized Gain			209		363
Equity Securities, FV-NI, Unrealized Loss			(34)		(3)
Equity Securities, Fair Value	670		670		851
Domestic Equity Securities [Member] | Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Equity Securities, Cost	15		15		14
Equity Securities, Accumulated Gross Unrealized Gain			5		12
Equity Securities, FV-NI, Unrealized Loss			0		0
Equity Securities, Fair Value	$ 20		20		$ 26
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			(107)
Debt Securities [Member] | Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
After tax amount of net unrealized gains recognized in AOCI			$ (28)

[1] The NDT Fund Investments table excludes cash and foreign currency of $1 million as of September 30, 2022, which is part of the NDT Fund.

[2] The NDT Fund Investments table excludes foreign currency of $2 million as of December 31, 2021, which is part of the NDT Fund.