Pension And OPEB (Schedule Of Pension And OPEB Costs) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Benefit Costs	$ 43	$ 18	$ 126	$ 76
Pension Benefits [Member] | Power [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Benefit Costs	14	6	39	24
Pension Benefits [Member] | PSE And G [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Benefit Costs	24	9	73	41
Pension Benefits [Member] | Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Benefit Costs	5	3	14	11
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Benefit Costs	26	19	77	62
OPEB [Member] | Power [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Benefit Costs	5	3	14	9
OPEB [Member] | PSE And G [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Benefit Costs	21	16	61	51
OPEB [Member] | Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Benefit Costs	$ 0	$ 0	$ 2	$ 2