Estimated capital costs to comply with existing and known federal and state air emissions regulations

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- Definition

Number Of Remediation Sites

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- Definition

Number of Energy Center Scrubbers to achieve compliance with regulations

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- Definition

Percentage of Rate Base Related to Carbon Dioxide Energy Centers

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No definition available.

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- Definition

Total costs accrued as of the balance sheet date for environmental loss contingencies.

+ 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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-Publisher FASB
-Name Accounting Standards Codification
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The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 50
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-Publisher FASB
-Name Accounting Standards Codification
-Glossary Asset Retirement Obligation
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- Definition

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

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Commitments And Contingencies (Environmental Matters) (Details) $ in Millions	Dec. 31, 2017 USD ($) site	Sep. 30, 2017 scrubber	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Percentage of Rate Base Related to Carbon Dioxide Energy Centers	17.00%
Asset Retirement Obligation	$ 644.0		$ 650.0	$ 623.0
Union Electric Company
Percentage of Rate Base Related to Carbon Dioxide Energy Centers	33.00%
Number of Energy Center Scrubbers \| scrubber		2
Asset Retirement Obligation	$ 640.0		644.0	617.0
Ameren Illinois Company
Asset Retirement Obligation	4.0		$ 6.0	$ 6.0
Manufactured Gas Plant
Accrual for environmental loss contingencies	$ 175.0
Manufactured Gas Plant \| Ameren Illinois Company
Number of remediation sites \| site	44
Accrual for environmental loss contingencies	$ 175.0
Sauget Area 2 \| Union Electric Company
Accrual for environmental loss contingencies	1.0
Minimum
Estimated capital costs to comply with existing and known federal and state air emissions regulations	325.0
Minimum \| Coal Combustion Residuals Estimate [Member]
Estimated capital costs to comply with existing and known federal and state air emissions regulations	300.0
Minimum \| Manufactured Gas Plant \| Ameren Illinois Company
Loss contingency, estimate of possible loss	175.0
Minimum \| Sauget Area 2 \| Union Electric Company
Loss contingency, estimate of possible loss	1.0
Maximum
Estimated capital costs to comply with existing and known federal and state air emissions regulations	425.0
Maximum \| Coal Combustion Residuals Estimate [Member]
Estimated capital costs to comply with existing and known federal and state air emissions regulations	350.0
Maximum \| Manufactured Gas Plant \| Ameren Illinois Company
Loss contingency, estimate of possible loss	249.0
Maximum \| Sauget Area 2 \| Union Electric Company
Loss contingency, estimate of possible loss	2.5
New CCR Rules Estimate [Member]
Asset Retirement Obligation	150.0
New CCR Rules Estimate [Member] \| Union Electric Company
Asset Retirement Obligation	$ 150.0