Consolidated Statement Of Cash Flows (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Interest Paid, Capitalized, Investing Activities	$ 48	$ 26	$ 17
Proceeds from Income Tax Refunds	49	0	0
Ameren Missouri
Interest Paid, Capitalized, Investing Activities	27	13	10
Proceeds from Income Tax Refunds	49	0	0
Ameren Illinois
Interest Paid, Capitalized, Investing Activities	$ 17	$ 12	$ 7