Financial Risk Management Activities (Schedule Providing Credit Risk From Others, Net Of Collateral) (Detail) (Power [Member], USD $) In Millions, unless otherwise specified	Mar. 31, 2014
Derivative [Line Items]
Current Exposure	$ 208
Securities held as Collateral	33
Net exposure	206
Number of Counterparties greater than 10%	1
Net Exposure of Counterparties greater than 10%	164
Investment Grade - External Rating [Member]
Derivative [Line Items]
Current Exposure	201
Securities held as Collateral	33
Net exposure	199
Number of Counterparties greater than 10%	1
Net Exposure of Counterparties greater than 10%	164	[1]
Non-Investment Grade - 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
Investment Grade - No External Rating [Member]
Derivative [Line Items]
Current Exposure	2
Securities held as Collateral	0
Net exposure	2
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	5
Securities held as Collateral	0
Net exposure	5
Number of Counterparties greater than 10%	0
Net Exposure of Counterparties greater than 10%	$ 0

[1] Represents net exposure with PSE&G.