Consolidated Statement Of Cash Flows (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Interest Paid, Capitalized, Investing Activities	$ 17	$ 16	$ 20
Union Electric Company
Interest Paid, Capitalized, Investing Activities	10	10	12
Ameren Illinois Company
Interest Paid, Capitalized, Investing Activities	$ 7	$ 6	$ 8