Financial Risk Management Activities (Schedule Providing Credit Risk From Others, Net Of Collateral) (Detail) - Power [Member] $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) Counterparty
Derivative [Line Items]
Current Exposure	$ 265
Collateral held from counterparties	12
Net Credit Exposure With Counterparties After Applying Collateral	253
Number of Counterparties greater than 10%	1
Net Exposure of Counterparties greater than 10%	$ 179
Number of active counterparties on credit risk derivatives | Counterparty	151
Investment Grade External Rating [Member]
Derivative [Line Items]
Credit exposure, percentage	99.00%
Investment Grade [Member]
Derivative [Line Items]
Current Exposure	$ 264
Collateral held from counterparties	12
Net Credit Exposure With Counterparties After Applying Collateral	252
Number of Counterparties greater than 10%	1
Net Exposure of Counterparties greater than 10%	179	[1]
Non-Investment Grade [Member]
Derivative [Line Items]
Current Exposure	1
Collateral held from counterparties	0
Net Credit Exposure With Counterparties After Applying Collateral	1
Number of Counterparties greater than 10%	0
Net Exposure of Counterparties greater than 10%	0
Letter of Credit [Member]
Derivative [Line Items]
Collateral held from counterparties	$ 12

[1] Represents net exposure with PSE&G.