Short-Term Debt And Liquidity (Schedule Of Maximum Aggregate Amount Available On Credit Agreements) (Details) $ in Millions	Dec. 31, 2024 USD ($)
Missouri Credit Agreement
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,400
Missouri Credit Agreement | Ameren (parent)
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	1,000
Missouri Credit Agreement | Ameren Missouri
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	1,000
Illinois Credit Agreement
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	1,200
Illinois Credit Agreement | Ameren (parent)
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	700
Illinois Credit Agreement | Ameren Illinois
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,000