Schedule II - Valuation And Qualifying Accounts (Details) - Allowance For Doubtful Accounts - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 29	$ 50	$ 17
Charged to Costs and Expenses	34	9	42
Charged to Other Accounts	4	0	6
Deductions	36	30	15
Balance at End of Period	31	29	50
Union Electric Company
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	13	16	7
Charged to Costs and Expenses	9	5	15
Charged to Other Accounts	0	0	0
Deductions	9	8	6
Balance at End of Period	13	13	16
Ameren Illinois Company
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	16	34	10
Charged to Costs and Expenses	25	4	27
Charged to Other Accounts	4	0	6
Deductions	27	22	9
Balance at End of Period	$ 18	$ 16	$ 34