Financial Risk Management Activities (Schedule Providing Credit Risk From Others, Net Of Collateral) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) Counterparty
Derivative [Line Items]
Current Exposure	$ 358
Collateral held from counterparties	186
Net Credit Exposure With Counterparties After Applying Collateral	172
Number of Counterparties greater than 10%	1
Net Exposure of Counterparties greater than 10%	$ 143
Number of active counterparties on credit risk derivatives | Counterparty	106
Investment Grade External Rating [Member]
Derivative [Line Items]
Credit exposure, percentage	99.80%
Investment Grade [Member]
Derivative [Line Items]
Current Exposure	$ 356
Collateral held from counterparties	185
Net Credit Exposure With Counterparties After Applying Collateral	171
Number of Counterparties greater than 10%	1
Net Exposure of Counterparties greater than 10%	143
Non-Investment Grade [Member]
Derivative [Line Items]
Current Exposure	2
Collateral held from counterparties	1
Net Credit Exposure With Counterparties After Applying Collateral	1
Number of Counterparties greater than 10%	0
Net Exposure of Counterparties greater than 10%	0
Public Service Electric and Gas Company
Derivative [Line Items]
Current Exposure	68
Letter of Credit [Member]
Derivative [Line Items]
Collateral held from counterparties	$ 186