SEGMENT OF BUSINESS INFORMATION (Details) (USD $) In Millions	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Segment reporting information
External Revenue	$ 1,092	$ 1,088	$ 3,374	$ 3,455
Operating Income	215	196	605	563
Net Income	105	101	289	281
Segment Assets	13,170	12,602	13,170	12,602	12,968
Electric Operations
Segment reporting information
External Revenue	728	705	1,903	1,820
Intersegment Revenue	2	3	6	7
Operating Income	225	201	487	426
Segment Assets	8,070	7,674	8,070	7,674
Gas Distribution
Segment reporting information
External Revenue	114	118	606	680
Intersegment Revenue	1	1	1	1
Operating Income	(11)	(8)	75	84
Segment Assets	2,099	2,062	2,099	2,062
Retail Gas Marketing
Segment reporting information
External Revenue	68	64	348	400
Net Income	(5)	(3)	14	21
Segment Assets	164	144	164	144
Energy Marketing
Segment reporting information
External Revenue	180	199	510	548
Intersegment Revenue	49	52	146	141
Net Income	2	1	4	3
Segment Assets	113	110	113	110
All Other
Segment reporting information
External Revenue	10	9	30	27
Intersegment Revenue	102	102	308	304
Operating Income	5	4	13	14
Net Income	(6)	(5)	(5)	(11)
Segment Assets	1,296	1,237	1,296	1,237
Adjustments/Eliminations
Segment reporting information
External Revenue	(8)	(7)	(23)	(20)
Intersegment Revenue	(154)	(158)	(461)	(453)
Operating Income	(4)	(1)	30	39
Net Income	114	108	276	268
Segment Assets	$ 1,428	$ 1,375	$ 1,428	$ 1,375

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

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