Consolidated Balance Sheet - AIC (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Accounts receivable - trade, allowance for doubtful accounts	$ 30	$ 31
Common Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	400,000,000.0	400,000,000.0
Common Stock, Shares, Outstanding	266,300,000	262,000,000.0
Ameren Illinois
Accounts receivable - trade, allowance for doubtful accounts	$ 18	$ 18
Common Stock, No Par Value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized	45,000,000.0	45,000,000.0
Common Stock, Shares, Outstanding	25,500,000	25,500,000