Trust Investments (Fair Values And Gross Unrealized Gains And Losses For The Securities) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022		Dec. 31, 2021
Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Cost	$ 2,130		$ 2,157
Gross Unrealized Gains	301		510
Gross Unrealized Losses	203		32
Fair Value	2,228	[1]	2,635	[2]
Nuclear Decommissioning Trust (NDT) Fund [Member] | Domestic Equity Securities [Member]
Schedule of Trust Investments [Line Items]
Cost	476		491
Equity Securities, FV-NI, Unrealized Gain	232		363
Gross Unrealized Losses	(12)		(3)
Fair Value	696		851
Nuclear Decommissioning Trust (NDT) Fund [Member] | International Equity Securities [Member]
Schedule of Trust Investments [Line Items]
Cost	336		346
Equity Securities, FV-NI, Unrealized Gain	68		119
Gross Unrealized Losses	(28)		(15)
Fair Value	376		450
Nuclear Decommissioning Trust (NDT) Fund [Member] | Equity Securities [Member]
Schedule of Trust Investments [Line Items]
Cost	812		837
Equity Securities, FV-NI, Unrealized Gain	300		482
Gross Unrealized Losses	(40)		(18)
Fair Value	1,072		1,301
Unrealized Gains (Losses) on Equity Securities still held	(163)
Nuclear Decommissioning Trust (NDT) Fund [Member] | Government Obligations [Member]
Schedule of Trust Investments [Line Items]
Cost	721		683
Gross Unrealized Gains	0		12
Gross Unrealized Losses	(94)		(8)
Fair Value	627		687
Nuclear Decommissioning Trust (NDT) Fund [Member] | Corporate Debt Securities [Member]
Schedule of Trust Investments [Line Items]
Cost	597		637
Gross Unrealized Gains	1		16
Gross Unrealized Losses	(69)		(6)
Fair Value	529		647
Nuclear Decommissioning Trust (NDT) Fund [Member] | Debt Securities [Member]
Schedule of Trust Investments [Line Items]
Cost	1,318		1,320
Gross Unrealized Gains	1		28
Gross Unrealized Losses	(163)		(14)
Fair Value	1,156		1,334
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent	(95)
Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Cost	213		226
Gross Unrealized Gains	6		18
Gross Unrealized Losses	36		2
Fair Value	183		242
Rabbi Trust [Member] | Domestic Equity Securities [Member]
Schedule of Trust Investments [Line Items]
Cost	14		14
Equity Securities, FV-NI, Unrealized Gain	6		12
Gross Unrealized Losses	0		0
Fair Value	20		26
Rabbi Trust [Member] | Equity Securities [Member]
Schedule of Trust Investments [Line Items]
Unrealized Gains (Losses) on Equity Securities still held	(6)
Rabbi Trust [Member] | Government Obligations [Member]
Schedule of Trust Investments [Line Items]
Cost	110		107
Gross Unrealized Gains	0		1
Gross Unrealized Losses	(21)		(1)
Fair Value	89		107
Rabbi Trust [Member] | Corporate Debt Securities [Member]
Schedule of Trust Investments [Line Items]
Cost	89		105
Gross Unrealized Gains	0		5
Gross Unrealized Losses	(15)		(1)
Fair Value	74		109
Rabbi Trust [Member] | Debt Securities [Member]
Schedule of Trust Investments [Line Items]
Cost	199		212
Gross Unrealized Gains	0		6
Gross Unrealized Losses	(36)		(2)
Fair Value	163		$ 216
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent	$ (26)

[1] 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.

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