Long-Term Debt and Equity Financings (Schedule of Required and Actual Debt Ratios) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Ameren Missouri
Debt Instrument [Line Items]
Bonds Issuable	$ 4,209
Preferred Stock Issuable Based On Coverage Ratio	2,701
Retired Bond Capacity	$ 1,959
Ameren Missouri | Actual Interest Coverage Ratio
Debt Instrument [Line Items]
Interest Coverage Ratio	3.3
Dividend Coverage Ratio	160.5
Ameren Illinois
Debt Instrument [Line Items]
Bonds Issuable	$ 8,517
Preferred Stock Issuable Based On Coverage Ratio	203
Retired Bond Capacity	$ 1,143
Ameren Illinois | Actual Interest Coverage Ratio
Debt Instrument [Line Items]
Interest Coverage Ratio	6.9
Dividend Coverage Ratio	3.8
Minimum | Ameren Missouri | Required Dividend Coverage Ratio
Debt Instrument [Line Items]
Interest Coverage Ratio	2.0
Dividend Coverage Ratio	2.5
Minimum | Ameren Illinois | Required Dividend Coverage Ratio
Debt Instrument [Line Items]
Interest Coverage Ratio	2.0
Dividend Coverage Ratio	1.5