Financial Risk Management Activities (Schedule Providing Credit Risk From Others, Net Of Collateral) (Detail) - Power [Member] $ in Millions	Mar. 31, 2017 USD ($) Counterparty
Derivative [Line Items]
Current Exposure	$ 442
Securities held as Collateral	95
Net exposure	347
Number of Counterparties greater than 10%	1
Amount Of Net Credit Exposure Greater Than Ten Percent	$ 202
Number Of Active Counterparties On Credit Risk Derivatives | Counterparty	159
Investment Grade [Member]
Derivative [Line Items]
Current Exposure	$ 433
Securities held as Collateral	94
Net exposure	339
Number of Counterparties greater than 10%	1
Amount Of Net Credit Exposure Greater Than Ten Percent	202	[1]
Non-Investment Grade [Member]
Derivative [Line Items]
Current Exposure	9
Securities held as Collateral	1
Net exposure	8
Number of Counterparties greater than 10%	0
Amount Of Net Credit Exposure Greater Than Ten Percent	0
Cash [Member]
Derivative [Line Items]
Securities held as Collateral	1
Letter of Credit [Member]
Derivative [Line Items]
Securities held as Collateral	$ 94

[1] Represents net exposure of $202 million with PSE&G.