Long-Term Debt And Equity Financings Long-Term Debt And Equity Financings (Schedule Of Environmental Bonds) (Details) - USD ($)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Debt instrument face amount	$ 1,000,000
Union Electric Company \| 1992 Series due 2022
Debt Instrument [Line Items]
Debt Instrument, Interest Rate During Period	2.58%	2.37%
Union Electric Company \| 1998 Series B due 2033
Debt Instrument [Line Items]
Debt Instrument, Interest Rate During Period	3.57%	2.79%
Union Electric Company \| 1998 Series C due 2033
Debt Instrument [Line Items]
Debt Instrument, Interest Rate During Period	3.43%	2.83%
Union Electric Company \| Environmental Improvement And Pollution Control Revenue Bonds \| 1992 Series due 2022
Debt Instrument [Line Items]
Debt instrument face amount	$ 47,000,000	$ 47,000,000
Long-term debt interest rate	1.60%
Debt Instrument, Interest Rate During Period	2.58%
Union Electric Company \| Environmental Improvement And Pollution Control Revenue Bonds \| Series A 1998 Due 2033 [Member]
Debt Instrument [Line Items]
Debt instrument face amount	$ 60,000,000
Long-term debt interest rate	2.90%
Debt Instrument, Interest Rate During Period	3.43%
Union Electric Company \| Environmental Improvement And Pollution Control Revenue Bonds \| 1998 Series B due 2033
Debt Instrument [Line Items]
Debt instrument face amount	$ 50,000,000	50,000,000
Long-term debt interest rate	2.90%
Debt Instrument, Interest Rate During Period	3.57%
Union Electric Company \| Environmental Improvement And Pollution Control Revenue Bonds \| 1998 Series C due 2033
Debt Instrument [Line Items]
Debt instrument face amount	$ 50,000,000	$ 50,000,000
Long-term debt interest rate	2.75%
Debt Instrument, Interest Rate During Period	3.43%

Face (par) amount of debt instrument at time of issuance.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

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- Definition

The average effective interest rate during the reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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