Revenue requirement for the electric energy-efficiency investment

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- Definition

Estimated Capital Project Costs

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- Definition

Ameren Illinois' electric energy efficiency investments under the FEJA.

+ References

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- Definition

Increase Decrease in Return on Equity for Energy Savings Goals

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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.

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- Definition

Amount of acquisition of long-lived, physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

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- Definition

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

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No definition available.

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- Definition

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

+ References

No definition available.

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- Definition

Percentage of public utility's approved return on equity.

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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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Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are expected to be recovered through revenue sources within one year or the normal operating cycle, if longer. Such costs are capitalized if they meet both of the following criteria: a. It is probable that future revenue in an amount at least equal to the capitalized cost will result from inclusion of that cost in allowable costs for rate-making purposes. b. Based on available evidence, the future revenue will be provided to permit recovery of the previously incurred cost rather than to provide for expected levels of similar future costs. If the revenue will be provided through an automatic rate-adjustment clause, this criterion requires that the regulator's intent clearly be to permit recovery of the previously incurred cost.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 340
-Section 50
-Paragraph 1
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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.

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Rate And Regulatory Matters (Narrative-Illinois) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	$ 1,127	$ 1,127	$ 1,230
Current regulatory assets	134	134	144
Ameren Illinois Company
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	759	759	822
Current regulatory assets	110	110	87
Ameren Transmission Company of Illinois
Public Utilities, General Disclosures [Line Items]
Estimated Capital Project Costs		81
Property, Plant and Equipment, Additions		38
Electricity \| Ameren Illinois Company
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount		50
Natural gas \| Ameren Illinois Company
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount		$ 15
Final Rate Order \| Electricity \| Ameren Illinois Company
Public Utilities, General Disclosures [Line Items]
Electric Energy-Efficiency Revenue Requirement	35
Final Rate Order \| Natural gas \| Ameren Illinois Company
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 32
Public Utilities, Approved Return on Equity, Percentage	9.87%
Public Utilities, Approved Equity Capital Structure, Percentage	50.00%
Rate Base	$ 1,600
TCJA - Reduction in Federal Statutory Income Tax Rate \| Natural gas \| Ameren Illinois Company
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	17
FEJA \| Electricity \| Ameren Illinois Company
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Return on Equity, Percentage		5.80%
Public Utilities, Approved Equity Capital Structure, Percentage		50.00%
Increase Decrease in Return on Equity for Energy Savings Goals		2.00%
FEJA 2019 through 2023 \| Electricity \| Ameren Illinois Company
Public Utilities, General Disclosures [Line Items]
FEJA Energy Efficiency Investments		$ 100
IEIMA \| 2018 IEIMA Revenue Requirement Reconciliation \| Electricity \| Ameren Illinois Company
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	16	16
IEIMA \| 2017 IEIMA Revenue Requirement Reconciliation \| Electricity \| Ameren Illinois Company
Public Utilities, General Disclosures [Line Items]
Current regulatory assets	54	$ 54
IEIMA \| 2016 IEIMA Revenue Requirement Reconciliation \| Electricity \| Ameren Illinois Company
Public Utilities, General Disclosures [Line Items]
Current regulatory assets			$ 24
IEIMA \| Final Rate Order \| Electricity \| Ameren Illinois Company
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	72
FEJA energy-efficiency rider [Domain] \| Final Rate Order \| Electricity \| Ameren Illinois Company
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 20