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, 2012
Power [Member]
Derivative [Line Items]
Credit exposure, percentage	94.00%
Current Exposure	$ 349
Securities held as Collateral	61
Net exposure	345
Number of Counterparties greater than 10%	2
Net Exposure of Counterparties greater than 10%	165
Number of active counterparties on credit risk derivatives	174
Power [Member] | Investment Grade - External Rating [Member]
Derivative [Line Items]
Current Exposure	317
Securities held as Collateral	61
Net exposure	313
Number of Counterparties greater than 10%	2
Net Exposure of Counterparties greater than 10%	165	[1]
Power [Member] | Non-Investment Grade - External Rating [Member]
Derivative [Line Items]
Current Exposure	22
Securities held as Collateral	0
Net exposure	22
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	10
Securities held as Collateral	0
Net exposure	10
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 exposure	0
Number of Counterparties greater than 10%	0
Net Exposure of Counterparties greater than 10%	0
PSE&G [Member]
Derivative [Line Items]
Net exposure	119
Nonaffiliated [Member]
Derivative [Line Items]
Net exposure	$ 46

[1] Includes net exposure of $119 million with PSE&G. The remaining net exposure of $46 million is with a nonaffiliated power purchaser which is a regulated investment grade counterparty.