Fair Value Measurements (Schedule Of Quantitative Information About Level 3 Fair Value Measurements) (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012
Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value	$ 22
Liabilities, Fair Value	0
PSE And G [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value	46
Liabilities, Fair Value	(104)
PSEG [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value	68
Liabilities, Fair Value	(104)
Electric Swaps [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value	18
Liabilities, Fair Value	1
Valuation Technique (s)	Discounted cash flow
Significant Unobservable Inputs	Power Basis
Various [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value	4	[1]
Liabilities, Fair Value	(1)	[1]
Forward Contracts [Member] | PSE And G [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value	46	[2]
Liabilities, Fair Value	$ (104)	[2]
Valuation Technique (s)	Discounted cash flow	[2]
Significant Unobservable Inputs	Long-Term Gas Basis and Capacity Prices	[2]
Minimum [Member] | MMBTU [Member] | Long-Term Gas Supply [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Longer-Term Basis Range	0
Minimum [Member] | MW-Day [Member] | Long-Term Electric Capacity [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Forecasted capacity prices	100
Minimum [Member] | MWh [Member] | Electric Swaps [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Power Basis Range	0
Maximum [Member] | MMBTU [Member] | Long-Term Gas Supply [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Longer-Term Basis Range	2
Maximum [Member] | MW-Day [Member] | Long-Term Electric Capacity [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Forecasted capacity prices	400
Maximum [Member] | MWh [Member] | Electric Swaps [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Power Basis Range	10

[1] Includes long-term electric capacity and long-term gas supply positions which are immaterial.

[2] Includes long-term gas supply and long-term electric capacity positions with various unobservable inputs. Significant unobservable inputs for the gas supply contracts include long-term basis prices in the range of $0 to $2/MMBTU of natural gas. Unobservable inputs for the long-term electric capacity contracts include forecasted capacity prices in the range of $100 to $400/MW day.