Other Income, Net (Other Income And Expenses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Other Nonoperating Income (Expense) [Line Items]
Allowance for equity funds used during construction	$ 76	$ 54	$ 43
Interest income on industrial development revenue bonds	0	1	24
Other interest income	41	32	11
Non-service cost components of net periodic benefit income	304	295	184
Miscellaneous income	9	7	10
Gain (Loss) on Extinguishment of Debt	16	0	0
Equity in earnings of subsidiaries	(4)	1	2
Donations	(5)	(24)	(26)
Miscellaneous expense	(20)	(18)	(22)
Total other income, net	417	348	226
Ameren Missouri
Other Nonoperating Income (Expense) [Line Items]
Allowance for equity funds used during construction	58	30	24
Interest income on industrial development revenue bonds	0	1	24
Other interest income	8	10	4
Non-service cost components of net periodic benefit income	139	97	55
Miscellaneous income	4	3	4
Donations	(2)	(2)	(3)
Miscellaneous expense	(11)	(9)	(9)
Total other income, net	196	130	99
Defined Benefit Plan, Non-service Cost or Income Components - Tracker	(41)	27	22
Ameren Illinois
Other Nonoperating Income (Expense) [Line Items]
Allowance for equity funds used during construction	17	19	18
Other interest income	32	21	7
Non-service cost components of net periodic benefit income	105	124	84
Miscellaneous income	4	4	5
Donations	(3)	(4)	(8)
Miscellaneous expense	(8)	(8)	(10)
Total other income, net	$ 147	$ 156	$ 96