Other Income, Net (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Other Nonoperating Income (Expense) [Line Items]
Allowance for equity funds used during construction	$ 12	$ 14	$ 31	$ 30
Interest income on industrial development revenue bonds	6	7	18	19
Non-service cost components of net periodic benefit income	45	34	138	102
Miscellaneous income	5	1	14	7
Income (Loss) from Equity Method Investments	(3)	2	1	8
Donations	(1)	(1)	(5)	(5)
Miscellaneous expense	(6)	(1)	(17)	(10)
Total Other Income, Net	58	56	180	151
Union Electric Company
Other Nonoperating Income (Expense) [Line Items]
Allowance for equity funds used during construction	7	7	17	17
Interest income on industrial development revenue bonds	6	7	18	19
Non-service cost components of net periodic benefit income	13	13	41	41
Miscellaneous income	2	2	5	3
Donations	0	0	(2)	(1)
Miscellaneous expense	(3)	(2)	(7)	(5)
Total Other Income, Net	25	27	72	74
Defined Benefit Plan, Non-service Cost or Income Components - Tracker	5	(3)	16	(6)
Ameren Illinois Company
Other Nonoperating Income (Expense) [Line Items]
Allowance for equity funds used during construction	5	7	14	13
Non-service cost components of net periodic benefit income	21	13	63	41
Miscellaneous income	4	0	9	4
Donations	(1)	(1)	(3)	(4)
Miscellaneous expense	(3)	0	(8)	(5)
Total Other Income, Net	$ 26	$ 19	$ 75	$ 49