SEGMENT OF BUSINESS INFORMATION (Details) (USD $) In Millions	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Segment reporting information
External Revenue	$ 1,000	$ 939	$ 2,281	$ 2,367
Operating Income	142	137	390	367
Income Available to Common Shareholders	56	54	184	180
Segment Assets	13,144	12,252	13,144	12,252	12,968
Electric Operations
Segment reporting information
External Revenue	616	575	1,174	1,115
Intersegment Revenue	2	2	4	4
Operating Income	140	139	262	225
Segment Assets	8,108	7,545	8,108	7,545
Gas Distribution
Segment reporting information
External Revenue	132	134	492	562
Operating Income	2	2	86	92
Segment Assets	2,178	2,060	2,178	2,060
Retail Gas Marketing
Segment reporting information
External Revenue	78	74	280	336
Income Available to Common Shareholders	(3)	(5)	19	24
Segment Assets	178	157	178	157
Energy Marketing
Segment reporting information
External Revenue	172	153	330	349
Intersegment Revenue	52	42	97	89
Income Available to Common Shareholders	1	2	2	2
Segment Assets	123	116	123	116
All Other
Segment reporting information
External Revenue	10	10	20	18
Intersegment Revenue	104	105	206	202
Operating Income	3	5	8	10
Income Available to Common Shareholders		(6)	1	(6)
Segment Assets	1,287	1,206	1,287	1,206
Adjustments/Eliminations
Segment reporting information
External Revenue	(8)	(7)	(15)	(13)
Intersegment Revenue	(158)	(149)	(307)	(295)
Operating Income	(3)	(9)	34	40
Income Available to Common Shareholders	58	63	162	160
Segment Assets	$ 1,270	$ 1,168	$ 1,270	$ 1,168

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 7
-Section 03
-Paragraph 12

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Topic 210
-SubTopic 10
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682
-Section S99
-Name Accounting Standards Codification
-Publisher FASB
-Paragraph 1

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Concepts (CON)
-Number 6
-Paragraph 25
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 18
-Article 5

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.18)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 9
-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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=6920599&loc=d3e1377-109256

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 131
-Paragraph 27
-Subparagraph b
-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.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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