Financial Risk Management Activities (Schedule Providing Credit Risk From Others, Net Of Collateral) (Detail) (Power [Member], USD $) In Millions, unless otherwise specified	Jun. 30, 2013
Derivative [Line Items]
Current Exposure	$ 245
Securities held as Collateral	36
Net exposure	245
Number of Counterparties greater than 10%	1
Net Exposure of Counterparties greater than 10%	114
Investment Grade - External Rating [Member]
Derivative [Line Items]
Current Exposure	225
Securities held as Collateral	36
Net exposure	225
Number of Counterparties greater than 10%	1
Net Exposure of Counterparties greater than 10%	114	[1]
Non-Investment Grade - External Rating [Member]
Derivative [Line Items]
Current Exposure	1
Securities held as Collateral	0
Net exposure	1
Number of Counterparties greater than 10%	0
Net Exposure of Counterparties greater than 10%	0
Investment Grade - No External Rating [Member]
Derivative [Line Items]
Current Exposure	8
Securities held as Collateral	0
Net exposure	8
Number of Counterparties greater than 10%	0
Net Exposure of Counterparties greater than 10%	0
Non-Investment Grade - No External Rating [Member]
Derivative [Line Items]
Current Exposure	11
Securities held as Collateral	0
Net exposure	11
Number of Counterparties greater than 10%	0
Net Exposure of Counterparties greater than 10%	$ 0

[1] Represents net exposure with PSE&G.