Achieved Percentage of Energy Efficiency Earnings For Incentive Award

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- Definition

Energy Efficiency Program Spending

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- Definition

Incentive Award if Energy Efficiency Goals Are Achieved

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- Definition

Incentive Award if Energy Efficiency Goals Are Achieved, Period

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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

Value established for a utility on which the entity is allowed to earn a particular rate of return

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No definition available.

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- Definition

Requested Rate Increase Related to Net Energy Costs

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No definition available.

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- Definition

Sharing Level For Fac

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No definition available.

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- Definition

Current regulatory liabilities generally represent obligations to make refunds to customers for various reasons including overpayment.

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- Definition

Amount of the cost of borrowed funds accounted for as interest expense.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.9)

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 9

-Article 9

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- Definition

Percentage of public utility's requested equity to capital, including debt and equity.

+ References

No definition available.

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- Definition

Amount of public utility's requested rate increase (decrease) with regulatory agency.

+ References

No definition available.

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- Definition

Percentage of public utility's requested return on equity.

+ References

No definition available.

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- Definition

Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are not expected to be recovered through revenue sources within one year or the normal operating cycle if longer.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 980

-SubTopic 340

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382

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Rate And Regulatory Matters Rate and Regulatory Matters (Narrative-Missouri) (Details) (USD $)	12 Months Ended			1 Months Ended	3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jul. 31, 2014	Dec. 31, 2014
Rate And Regulatory Matters [Line Items]
Regulatory assets	$ 1,582,000,000us-gaap_RegulatoryAssetsNoncurrent	$ 1,240,000,000us-gaap_RegulatoryAssetsNoncurrent			$ 1,582,000,000us-gaap_RegulatoryAssetsNoncurrent
Interest Expense	341,000,000us-gaap_InterestExpense	398,000,000us-gaap_InterestExpense	392,000,000us-gaap_InterestExpense
Union Electric Company
Rate And Regulatory Matters [Line Items]
Regulatory assets	695,000,000	534,000,000			695,000,000
Interest Expense	211,000,000	210,000,000	223,000,000
Electric Distribution \| Pending Rate Case [Member] \| Union Electric Company
Rate And Regulatory Matters [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount				190,000,000
Requested Rate Increase Related to Net Energy Costs				100,000,000
Sharing Level For Fac				95.00%
Public Utilities, Requested Return on Equity, Percentage				10.40%
Public Utilities, Requested Equity Capital Structure, Percentage				51.80%
Rate Base				7,000,000,000
Electric Distribution \| Accounting Authority Order Request \| Union Electric Company
Rate And Regulatory Matters [Line Items]
Regulatory assets	36,000,000				36,000,000
MEEIA \| Electric Distribution \| Union Electric Company
Rate And Regulatory Matters [Line Items]
Energy Efficiency Program Spending					135,000,000
Incentive Award if Energy Efficiency Goals Are Achieved					25,000,000
Achieved Percentage of Energy Efficiency Earnings For Incentive Award	100.00%				100.00%
Incentive Award if Energy Efficiency Goals Are Achieved, Period					3 years
Minimum Percentage of Energy Efficiency Goal Achievement For Company To Be Eligible For Incentive Award					70.00%
MOPSC [Member] \| Electric Distribution \| Pending Rate Case [Member] \| Union Electric Company
Rate And Regulatory Matters [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount					89,000,000
Public Utilities, Requested Return on Equity, Percentage					9.25%
Fac Prudence Review \| Subsequent Periods After September 30, 2009 \| Union Electric Company
Rate And Regulatory Matters [Line Items]
Customer Refund Liability, Current	26,000,000				26,000,000
Interest Expense	$ 1,000,000