Other Income, Net (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Other Nonoperating Income (Expense) [Line Items]
Allowance for equity funds used during construction	$ 9	$ 8
Interest income on industrial development revenue bonds	1	6
Non-service cost components of net periodic benefit income	64	46
Miscellaneous income	9	4
Income (Loss) from Equity Method Investments	2	3
Donations	(2)	(2)
Miscellaneous expense	(5)	(5)
Total Other Income, Net	78	60
Union Electric Company
Other Nonoperating Income (Expense) [Line Items]
Allowance for equity funds used during construction	4	4
Interest income on industrial development revenue bonds	1	6
Non-service cost components of net periodic benefit income	14	14
Miscellaneous income	4	2
Donations	(1)	(1)
Miscellaneous expense	(3)	(2)
Total Other Income, Net	19	23
Defined Benefit Plan, Non-service Cost or Income Components - Tracker	17	6
Ameren Illinois Company
Other Nonoperating Income (Expense) [Line Items]
Allowance for equity funds used during construction	4	4
Non-service cost components of net periodic benefit income	31	21
Miscellaneous income	5	2
Donations	(1)	(1)
Miscellaneous expense	(2)	(2)
Total Other Income, Net	$ 37	$ 24