Financial Risk Management Activities (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Net cash collateral received in connection with net derivative contracts	$ 4	$ 24
Aggregate fair value of derivative contracts in a liability position that contains triggers for additional collateral	104	127
Additional collateral aggregate fair value	881	945
Power [Member]
Derivatives, Fair Value [Line Items]
Amount of after-tax gains on derivatives designated and effective as cash flow hedges expected to be reclassified to earnings during the 12 months following period end	1
Credit exposure, percentage	96.70%
Number of active counterparties on credit risk derivatives	144
Power [Member] | Senior Notes 5.32% Due September 2016 [Member]
Derivatives, Fair Value [Line Items]
Senior Notes converted into variable rate debt	300
PSEG [Member]
Derivatives, Fair Value [Line Items]
Aggregate amount of series of interest rate swaps converting to variable-rate debt	850
Senior Notes converted into variable rate debt	303
Fair value of interest rate swaps designated as underlying hedges	18	22
Aggregate fair value of derivative contracts in a liability position that contains triggers for additional collateral	26	18
Additional collateral aggregate fair value	78	109
Amount of reduction in interest expense attributed to interest rate swaps designated as fair value hedges	5
PSEG [Member] | Senior Notes 5.5% Due December 2015 [Member]
Derivatives, Fair Value [Line Items]
Senior Notes converted into variable rate debt	300
Stated interest rate of debt instrument	5.50%
PSEG [Member] | Senior Notes 5.32% Due September 2016 [Member]
Derivatives, Fair Value [Line Items]
Stated interest rate of debt instrument	5.32%
PSEG [Member] | Senior Notes 2.75% Due September 2016 [Member]
Derivatives, Fair Value [Line Items]
Senior Notes converted into variable rate debt	250
Stated interest rate of debt instrument	2.75%
Non Current Assets [Member]
Derivatives, Fair Value [Line Items]
Net cash collateral received in connection with net derivative contracts	$ (3)	$ (8)