Supplemental Information (Schedule of Excise Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accounting Policies [Line Items]
Excise Tax Expense	$ 295	$ 275	$ 254
Union Electric Company
Accounting Policies [Line Items]
Excise Tax Expense	162	150	139
Ameren Illinois Company
Accounting Policies [Line Items]
Excise Tax Expense	$ 133	$ 125	$ 115