Short-Term Debt And Liquidity (Narrative) (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) lender	Dec. 31, 2022
Utilities
Short-term Debt [Line Items]
Average interest rate	5.29%	1.95%
Multiyear Credit Facility
Short-term Debt [Line Items]
Number of lenders | lender	21
Line of credit facility, maximum borrowing capacity, per lender	$ 156,000,000
Multiyear Credit Facility
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	2,600,000,000
Commitment fee amount	$ 100,000,000
Actual debt-to-capital ratio	0.59
Multiyear Credit Facility | Maximum
Short-term Debt [Line Items]
Actual debt-to-capital ratio	0.65
Missouri Credit Agreement
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,400,000,000
Missouri Credit Agreement | Ameren Missouri
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,000,000,000
Actual debt-to-capital ratio	0.50
Missouri Credit Agreement | Multiyear Credit Facility
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,700,000,000
Illinois Credit Agreement
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	1,200,000,000
Illinois Credit Agreement | Ameren Illinois
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,000,000,000
Actual debt-to-capital ratio	0.46
Illinois Credit Agreement | Multiyear Credit Facility
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,500,000,000
Credit Agreements
Short-term Debt [Line Items]
Net liquidity available	2,100,000,000
Covenant terms, default provisions, maximum indebtedness	$ 100,000,000