Collateral to be posted if credit ratings are below investment grade

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- Definition

Disposal Group, Including Discontinued Operation, Buyer's Indemnification Guarantee Obligation

+ References

No definition available.

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- Definition

Guarantees, Maximum Exposure

+ References

No definition available.

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- Definition

Guarantees Outstanding

+ References

No definition available.

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- Definition

Proceeds from Asset Sale Held in Escrow

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No definition available.

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

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No definition available.

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- Definition

Amount of loss contingency liability.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 1

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- Definition

The estimated maximum amount of possible loss from the contingency.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (b)

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- Definition

An amount representing an agreement for an unconditional promise by the maker to pay the Company (holder) a definite sum of money within one year from the balance sheet date (or the normal operating cycle, whichever is longer), net of any write-downs taken for collection uncertainty on the part of the holder. Such amount may include accrued interest receivable in accordance with the terms of the debt. The debt also may contain provisions and related items including a discount or premium, payable on demand, secured, or unsecured, interest bearing or noninterest bearing, among a myriad of other features and characteristics. This amount does not include amounts related to receivables held-for-sale.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

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-Subparagraph (SX 210.5-02.3)

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-Name Regulation S-X (SX)

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- Definition

Aggregate cash proceeds received from a combination of transactions in which noncurrent assets are sold, which may include the sale of a business, an investment in an affiliate (including an equity method investee), property, plant and equipment and intangible assets. Excludes sales of trading, available-for-sale, and held-to-maturity securities.

+ References

No definition available.

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Divestiture Transactions and Discontinued Operations (Narrative) (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended
	Jan. 31, 2014	Dec. 31, 2013	Mar. 31, 2015	Dec. 31, 2014	Mar. 14, 2013
New Ameren Energy Resources Company, LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Notes, Loans and Financing Receivable, Net, Current			$ 12	$ 12
Range of possible loss maximum			25.0
Collateral to be posted if credit ratings are below investment grade			20
Buyer's indemnification guarantee obligation					25
Loss contingency accrual			25
Guarantees Outstanding			105
Letters of Credit Outstanding, Amount			9
Elgin, Gibson City and Grand Tower Energy Centers
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Sales of Business, Affiliate and Productive Assets	168.0	137.5
Proceeds from Asset Sale Held in Escrow	17
Ameren Energy Marketing Company [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Guarantees Outstanding			103
Guarantees, Maximum Exposure			10
Guarantee Type, Other [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Guarantees Outstanding			2
Guarantees, Maximum Exposure			$ 1