OTHER FINANCIAL DATA - VARIABLE INTEREST ENTITIES (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Variable Interest Entities Disclosure [Abstract]
Secured debt of variable interest entity	$ 347		$ 347
Amounts Associated With Variable Interest Entities, Cost of Electric Fuel And Purchased Power	(26)	(29)	(66)	(55)
Amounts Associated With Variable Interest Entities, Operation And Maintenance	4	1	15	23
Amounts Associated With Variable Interest Entities, Depreciation And Amortization	7	7	19	20
Amounts Associated With Variable Interest Entities, Total Operating Expenses	(15)	(21)	(32)	(12)
Amounts Associated With Variable Interest Entities, Operating Income	15	21	32	12
Amounts Associated With Variable Interest Entities, Other Income (Expense), Net		4	(1)
Amounts Associated With Variable Interest Entities, Interest Expense	(3)	(4)	(8)	(6)
Amounts Associated With Variable Interest Entities, Net Income	12	21	23	6
Amounts Associated With Variable Interest Entities, (Earnings) Losses Attributable Noncontrolling Interests	$ (12)	$ (21)	$ (23)	$ (6)