Achieved Percentage of Energy Efficiency Earnings For Incentive Award

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- Definition

Energy Efficiency Program Spending

+ References

No definition available.

+ Details

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- Definition

Incentive Award if Energy Efficiency Goals Are Achieved

+ References

No definition available.

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- Definition

Incentive Award if Energy Efficiency Goals Are Achieved, Period

+ 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.

+ Details

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- Definition

Noranda Contract Term

+ 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

+ References

No definition available.

+ Details

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

Amount of public utility's approved rate increase (decrease) by regulatory agency.

+ References

No definition available.

+ Details

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- Definition

Percentage of public utility's approved return on equity.

+ References

No definition available.

+ Details

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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 (Narrative-Missouri) (Detail) (USD $)	3 Months Ended		1 Months Ended
	Dec. 31, 2014	Mar. 31, 2015	Apr. 30, 2015
Rate And Regulatory Matters [Line Items]
Regulatory assets	$ 1,582,000,000us-gaap_RegulatoryAssetsNoncurrent	1,577,000,000us-gaap_RegulatoryAssetsNoncurrent
Union Electric Company
Rate And Regulatory Matters [Line Items]
Regulatory assets	695,000,000	687,000,000
Electric Distribution [Member] \| Union Electric Company \| MEEIA [Member]
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%
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%
Electric Distribution [Member] \| Union Electric Company \| Final Rate Order [Member]
Rate And Regulatory Matters [Line Items]
Long-term Contract for Purchase of Electric Power, Date of Contract Expiration		15 years
Electric Distribution [Member] \| Union Electric Company \| Accounting Authority Order Request [Member]
Rate And Regulatory Matters [Line Items]
Regulatory assets		36,000,000
Subsequent Event [Member] \| Electric Distribution [Member] \| Union Electric Company \| Final Rate Order [Member]
Rate And Regulatory Matters [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount			122,000,000
Public Utilities, Approved Return on Equity, Percentage			9.53%
Public Utilities, Approved Equity Capital Structure, Percentage			51.80%
Rate Base			7,000,000,000
Subsequent Event [Member] \| Electric Distribution - Net Energy Costs [Member] \| Union Electric Company \| Final Rate Order [Member]
Rate And Regulatory Matters [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount			109,000,000
Subsequent Event [Member] \| Electric Distribution - Non-Energy Costs [Member] \| Union Electric Company \| Final Rate Order [Member]
Rate And Regulatory Matters [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount			$ 13,000,000