Short-Term Debt And Liquidity (Narrative) (Details)	12 Months Ended
	Dec. 31, 2022 USD ($) lender	Dec. 31, 2021
Multiyear Credit Facility
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	$ 2,600,000,000
Line of Credit Facility, 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 2012
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,400,000,000
Illinois Credit Agreement 2012
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	1,200,000,000
Credit Agreements
Short-term Debt [Line Items]
Net Liquidity Available	1,500,000,000
Covenant terms, default provisions, maximum indebtedness	100,000,000
Parent Company | Missouri Credit Agreement 2012
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	1,000,000,000
Parent Company | Illinois Credit Agreement 2012
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	700,000,000
Union Electric Company | Missouri Credit Agreement 2012
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,000,000,000
Actual debt-to-capital ratio	0.49
Ameren Illinois Company | Illinois Credit Agreement 2012
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,000,000,000
Actual debt-to-capital ratio	0.46
Utilities [Member]
Short-term Debt [Line Items]
Short Term Debt, Weighted Average Interest Rate During Period	1.95%	0.17%
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 | Missouri Credit Agreement 2012
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	1,700,000,000
Multiyear Credit Facility | Illinois Credit Agreement 2012
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,500,000,000