Financial Risk Management Activities (Schedule Providing Credit Risk From Others, Net Of Collateral) (Detail) $ in Millions	Sep. 30, 2015 USD ($)
Power [Member]
Derivative [Line Items]
Current Exposure	$ 364
Securities held as Collateral	118
Net exposure	246
Number of Counterparties greater than 10%	2
Amount Of Net Credit Exposure Greater Than Ten Percent	127
Power [Member] | Investment Grade - External Rating [Member]
Derivative [Line Items]
Current Exposure	348
Securities held as Collateral	118
Net exposure	230
Number of Counterparties greater than 10%	2
Amount Of Net Credit Exposure Greater Than Ten Percent	127	[1]
Power [Member] | 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
Amount Of Net Credit Exposure Greater Than Ten Percent	0
Power [Member] | 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
Amount Of Net Credit Exposure Greater Than Ten Percent	0
Power [Member] | Non-Investment Grade - No External Rating [Member]
Derivative [Line Items]
Current Exposure	4
Securities held as Collateral	0
Net exposure	4
Number of Counterparties greater than 10%	0
Amount Of Net Credit Exposure Greater Than Ten Percent	0
PSE And G [Member] | Investment Grade - External Rating [Member]
Derivative [Line Items]
Net exposure	$ 87

[1] net exposure of $87 million with PSE&G.