Consolidated Balance Sheet - UE (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Accounts receivable - trade, allowance for doubtful accounts	$ 29	$ 50
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	257,700,000	253,300,000
Union Electric Company
Accounts receivable - trade, allowance for doubtful accounts	$ 13	$ 16
Common Stock, No Par Value (in dollars per share)	$ 5	$ 5
Common stock, shares authorized	150,000,000.0	150,000,000.0
Common Stock, Shares, Outstanding	102,100,000	102,100,000