Amount of anticipated decommissioning costs included in annual costs of service used to establish electric rates.

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- Definition

The number of mills per nuclear-generated kilowatt hour sold (one mill = 1/10 of one cent) charged by the Department of Energy for future disposal of spent nuclear fuel, referred to as the NWF fee. This fee is collected from electric customers who use power generated by the Callaway nuclear plant.

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- Definition

Amount of gain recognized in the period that had been disclosed in prior periods as a contingent gain.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 17

-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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 30

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6397426&loc=d3e17499-108355

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- Definition

The amount or range of possible amounts of gain that could be realized upon the resolution of a contingency.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 17

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 450

-SubTopic 30

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6397426&loc=d3e17499-108355

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- Definition

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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Callaway Energy Center (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Loss Contingencies [Line Items]
Number of mills charged for NWF fee	1
Costs incurred to be recovered	$ 13
Settlement payment	11
Annual decommissioning costs included in costs of service		7	7	7
Reduction To Depreciation And Amortization [Member]
Loss Contingencies [Line Items]
Settlement payment	2
Reduction To Other Operations And Maintenance [Member]
Loss Contingencies [Line Items]
Settlement payment	2
Reduction In Property And Plant [Member]
Loss Contingencies [Line Items]
Settlement payment	$ 7