Accumulated Other Comprehensive Income (Loss), Net Of Tax (Schedule Of Accumulated Other Comprehensive Income (Loss)) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Dec. 31, 2010
Derivative Contracts	$ 11	$ 31	$ 31	$ 111
Pension and OPEB Plans	(415)	(438)	(324)	(377)
NDT Fund	77	66	32	109
Other	5	4	5	1
Accumulated Other Comprehensive Income (Loss)	(322)	(337)	(256)	(156)
Power [Member]
Accumulated Other Comprehensive Income (Loss)	(265)	(276)
PSE And G [Member]
Accumulated Other Comprehensive Income (Loss)	2	2
Other Comprehensive Income (Loss) [Member] | Power [Member]
Derivative Contracts	(21)		(80)
Pension and OPEB Plans	21		45
NDT Fund	11		(77)
Other	0		0
Accumulated Other Comprehensive Income (Loss)	11		(112)
Other Comprehensive Income (Loss) [Member] | PSE And G [Member]
Derivative Contracts	0		0
Pension and OPEB Plans	0		0
NDT Fund	0		0
Other	0		2
Accumulated Other Comprehensive Income (Loss)	0		2
Other Comprehensive Income (Loss) [Member] | Other [Member]
Derivative Contracts	1		0
Pension and OPEB Plans	2		8
NDT Fund	0		0
Other	1		2
Accumulated Other Comprehensive Income (Loss)	$ 4		$ 10