Financial Risk Management Activities (Schedule Providing Credit Risk From Others, Net Of Collateral) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014 Counterparty
Power [Member]
Derivative [Line Items]
Credit exposure, percentage	100.00%
Current Exposure	$ 444
Securities held as Collateral	51
Net Credit Exposure With Counterparties After Applying Collateral	432
Number of Counterparties greater than 10%	2
Net Exposure of Counterparties greater than 10%	259
Number of active counterparties on credit risk derivatives	148
Power [Member] | Investment Grade - External Rating [Member]
Derivative [Line Items]
Current Exposure	436
Securities held as Collateral	51
Net Credit Exposure With Counterparties After Applying Collateral	425
Number of Counterparties greater than 10%	2
Net Exposure of Counterparties greater than 10%	259	[1]
Power [Member] | Non-Investment Grade - External Rating [Member]
Derivative [Line Items]
Current Exposure	2
Securities held as Collateral	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
Power [Member] | Investment Grade - No External Rating [Member]
Derivative [Line Items]
Current Exposure	6
Securities held as Collateral	0
Net Credit Exposure With Counterparties After Applying Collateral	6
Number of Counterparties greater than 10%	0
Net Exposure of Counterparties greater than 10%	0
Power [Member] | Non-Investment Grade - No External Rating [Member]
Derivative [Line Items]
Current Exposure	0
Securities held as Collateral	0
Net Credit Exposure With Counterparties After Applying Collateral	0
Number of Counterparties greater than 10%	0
Net Exposure of Counterparties greater than 10%	0
PSE&G [Member] | Investment Grade - External Rating [Member]
Derivative [Line Items]
Net Credit Exposure With Counterparties After Applying Collateral	206
Nonaffiliated [Member] | Investment Grade - External Rating [Member]
Derivative [Line Items]
Net Credit Exposure With Counterparties After Applying Collateral	$ 53

[1] et exposure of $206 million with PSE&G. The remaining net exposure of $53 million is with a nonaffiliated power purchaser which is a regulated investment grade counterparty.