Achieved Percentage Of Energy Efficiency Earnings For Incentive Award

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- Definition

Authorized increase in revenue from utility service.

+ References

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- Definition

Contested Amounts Under the FAC

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- Definition

Energy Efficiency program spending.

+ References

No definition available.

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- Definition

Incentive award if energy efficiency goals are achieved.

+ References

No definition available.

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- Definition

Minimum percentage of energy efficiency goal achievement for company to be eligible for incentive award.

+ References

No definition available.

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- Definition

Number of years energy efficiency spending will occur.

+ References

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- Definition

Percentage of projected lost revenue included in rates.

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- Definition

Rate Of Return On Equity

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- Definition

Remaining percentage of projected lost revenues expected to be recovered as part of future rate proceedings.

+ References

No definition available.

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- Definition

Time required, in months, to complete FAC prudence reviews

+ References

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- Definition

Utility Revenue Increase Requested

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- Definition

Amount of regulatory costs not yet approved by the regulatory authority.

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- Definition

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section 45

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-Publisher FASB

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-Glossary Cash Equivalents

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 1

-Article 5

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The cost of borrowed funds accounted for as interest that was charged against earnings during the period.

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-LegacyDoc This is a non-GAAP reference that was included in the 2009 taxonomy. It will be removed from future versions of this taxonomy.

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-Topic 942

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-Subparagraph (SX 210.9-04.9)

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Rate And Regulatory Matters (Narrative-Missouri) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended				1 Months Ended						1 Months Ended	6 Months Ended		1 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011	Dec. 31, 2010	Apr. 30, 2011 Ameren Missouri [Member] Fac Prudence Review [Member]	Sep. 30, 2011 Ameren Missouri [Member] Fac Prudence Review [Member] Month	Jul. 31, 2011 Ameren Missouri [Member] Accounting Authority Order Request [Member] Fac Prudence Review [Member]	Jan. 31, 2009 Electric Distribution [Member] Ameren Missouri [Member] 2009 Final Rate Order [Member]	Jul. 31, 2011 Electric Distribution [Member] Ameren Missouri [Member] Final Rate Order [Member]	May 31, 2010 Electric Distribution [Member] Ameren Missouri [Member] Final Rate Order [Member]	Feb. 03, 2012 Electric Distribution [Member] Ameren Missouri [Member] Pending Rate Case [Member]	Jun. 30, 2012 Electric Distribution [Member] Ameren Missouri [Member] Pending Rate Case [Member] MoPSC Staff Position [Member]	Feb. 29, 2012 Electric Distribution [Member] Ameren Missouri [Member] Pending Rate Case [Member] MEEIA Agreement [Member]	Feb. 29, 2012 Electric Distribution [Member] Ameren Missouri [Member] Pending Rate Order [Member] MEEIA Agreement [Member] Year	Feb. 29, 2012 Subsequent Periods After September 30, 2009 [Member] Mopsc Staff Report [Member] Fac Prudence Review [Member]
Rate And Regulatory Matters [Line Items]
Cash received	$ 117	$ 378	$ 117	$ 378	$ 255	$ 545				$ 21		$ 16
Authorized increase in revenue from utility service											173
Utility revenue increase requested													376	210	80
Return on equity													10.75%	9.00%
Energy Efficiency program spending																147
Number of years energy efficiency spending will occur																3
Lost revenue from customers																90.00%
Remaining loss from customers																10.00%
Energy effciency																19
Energy efficiency percentage for incentive award																100.00%
Minimum percentage of energy efficiency goal achievement for company to be eligible for incentive award																70.00%
Time required to complete FAC prudence reviews, in months								18
Contested amounts under the FAC							18										26
Interest Charges	112	104	225	223			1
Request to defer fixed costs not recovered from Noranda, amount									$ 36