Long-Term Debt And Equity Financings (Schedule Of Average Interest Rates) (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
1998 Series A due 2033 | Union Electric Company
Debt Instrument [Line Items]
Debt instrument, interest rate during period	2.76%	1.77%
1998 Series B due 2033 | Union Electric Company
Debt Instrument [Line Items]
Debt instrument, interest rate during period	2.79%	1.75%
1998 Series C due 2033 | Union Electric Company
Debt Instrument [Line Items]
Debt instrument, interest rate during period	2.83%	1.73%
Series B-1 1993 Due 2028 | Ameren Illinois Company
Debt Instrument [Line Items]
Debt instrument, interest rate during period	1.58%	1.08%
1992 Series due 2022 | Union Electric Company
Debt Instrument [Line Items]
Debt instrument, interest rate during period	2.37%	1.43%