Financial Risk Management Activities (Schedule Providing Credit Risk From Others, Net Of Collateral) (Detail) - Power [Member] $ in Millions	Jun. 30, 2017 USD ($) Counterparty
Derivative [Line Items]
Current Exposure	$ 429
Securities held as Collateral	92
Net exposure	337
Number of Counterparties greater than 10%	1
Amount Of Net Credit Exposure Greater Than Ten Percent	$ 130
Number Of Active Counterparties On Credit Risk Derivatives | Counterparty	152
Investment Grade [Member]
Derivative [Line Items]
Current Exposure	$ 420
Securities held as Collateral	92
Net exposure	328
Number of Counterparties greater than 10%	1
Amount Of Net Credit Exposure Greater Than Ten Percent	130	[1]
Non-Investment Grade [Member]
Derivative [Line Items]
Current Exposure	9
Securities held as Collateral	0
Net exposure	9
Number of Counterparties greater than 10%	0
Amount Of Net Credit Exposure Greater Than Ten Percent	0
Letter of Credit [Member]
Derivative [Line Items]
Securities held as Collateral	$ 92

[1] Represents net exposure of $130 million with PSE&G.