Long-Term Debt And Equity Financings Long-Term Debt And Equity Financings (Schedule Of Environmental Bonds) (Details) - Union Electric Company - Environmental Improvement And Pollution Control Revenue Bonds - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
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%
Series A 1998 Due 2033
Debt Instrument [Line Items]
Debt instrument face amount	$ 60,000,000
Debt Instrument, Interest Rate During Period	3.43%
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%
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%
1998 Series A due 2033
Debt Instrument [Line Items]
Debt instrument face amount	$ 60,000,000	$ 60,000,000
Long-term debt interest rate	2.90%