Other Income, Net (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Other Nonoperating Income (Expense) [Line Items]
Allowance for equity funds used during construction	$ 23	$ 16	$ 48	$ 39
Interest income on industrial development revenue bonds	0	0	0	1
Other interest income	8	6	29	23
Non-service cost components of net periodic benefit income	76	84	228	211
Miscellaneous income	0	1	6	4
Income (Loss) from Equity Method Investments	(2)	0	(1)	2
Donations	(1)	(1)	(5)	(5)
Miscellaneous expense	(3)	(5)	(12)	(14)
Total Other Income, Net	101	101	293	261
Union Electric Company
Other Nonoperating Income (Expense) [Line Items]
Allowance for equity funds used during construction	15	8	38	20
Interest income on industrial development revenue bonds	0	0	0	1
Other interest income	2	3	7	8
Non-service cost components of net periodic benefit income	35	34	104	62
Miscellaneous income	1	1	3	3
Donations	0	0	(2)	(2)
Miscellaneous expense	(2)	(2)	(6)	(7)
Total Other Income, Net	51	44	144	85
Defined Benefit Plan, Non-service Cost or Income Components - Tracker	(11)	(2)	(31)	32
Ameren Illinois Company
Other Nonoperating Income (Expense) [Line Items]
Allowance for equity funds used during construction	8	5	10	15
Other interest income	7	4	22	14
Non-service cost components of net periodic benefit income	25	31	78	93
Miscellaneous income	0	0	3	2
Donations	0	(1)	(2)	(3)
Miscellaneous expense	(3)	(2)	(6)	(6)
Total Other Income, Net	$ 37	$ 37	$ 105	$ 115