Financial Risk Management Activities (Schedule Of Gross Volume, On Absolute Basis For Derivative Contracts) (Detail) $ / mwh in Millions, $ / Derivative in Millions, $ / DTH in Millions	12 Months Ended
	Dec. 31, 2022 $ / Derivative $ / mwh $ / DTH	Dec. 31, 2021 $ / mwh $ / DTH $ / Derivative
Natural Gas Dth [Member]
Derivative [Line Items]
Gross volume of derivative on absolute value basis | $ / DTH	49	47
Electricity MWh [Member]
Derivative [Line Items]
Gross volume of derivative on absolute value basis	(60)	(76)
FTRs MWh [Member]
Derivative [Line Items]
Gross volume of derivative on absolute value basis	24	27
Interest Rate Swaps [Member]
Derivative [Line Items]
Gross volume of derivative on absolute value basis | $ / Derivative	1,050	0