Trust Investments (Proceeds From The Sales Of And The Net Realized Gains On Securities in the NDT and Rabbi Trusts) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Schedule of Trust Investments [Line Items]
Proceeds from Sale of Trust Investments		$ 501	$ 662
Net Gains (Losses) on Trust Investments		(68)	60
Nuclear Decommissioning Trust (NDT) Fund [Member]
Schedule of Trust Investments [Line Items]
Proceeds from Sale of Trust Investments	[1]	473	597
Gross Realized Gains		29	79
Gross Realized Losses		(34)	(15)
Net Realized Gains (Losses)	[2]	(5)	64
Unrealized Gain (Loss) on Equity Securities		(61)	(7)
Net Gains (Losses) on Trust Investments		(66)	57
Rabbi Trust [Member]
Schedule of Trust Investments [Line Items]
Proceeds from Sale of Trust Investments		28	65
Gross Realized Gains		1	5
Gross Realized Losses		(2)	(2)
Net Realized Gains (Losses)		(1)	3
Unrealized Gain (Loss) on Equity Securities		(1)	0
Net Gains (Losses) on Trust Investments		$ (2)	$ 3

[1] Includes activity in accounts related to the liquidation of funds being transitioned within the trust.

[2] The cost of these securities was determined on the basis of specific identification.