Other Income, Net (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Other Nonoperating Income (Expense) [Line Items]
Allowance for equity funds used during construction	$ 16	$ 12	$ 39	$ 31
Interest income on industrial development revenue bonds	0	6	1	18
Other interest income	6	2	23	6
Non-service cost components of net periodic benefit income	84	45	211	138
Miscellaneous income	1	3	4	8
Income (Loss) from Equity Method Investments	0	(3)	2	1
Donations	(1)	(1)	(5)	(5)
Miscellaneous expense	(5)	(6)	(14)	(17)
Total Other Income, Net	101	58	261	180
Union Electric Company
Other Nonoperating Income (Expense) [Line Items]
Allowance for equity funds used during construction	8	7	20	17
Interest income on industrial development revenue bonds	0	6	1	18
Other interest income	3	1	8	2
Non-service cost components of net periodic benefit income	34	13	62	41
Miscellaneous income	1	1	3	3
Donations	0	0	(2)	(2)
Miscellaneous expense	(2)	(3)	(7)	(7)
Total Other Income, Net	44	25	85	72
Defined Benefit Plan, Non-service Cost or Income Components - Tracker	(2)	5	32	16
Ameren Illinois Company
Other Nonoperating Income (Expense) [Line Items]
Allowance for equity funds used during construction	5	5	15	14
Other interest income	4	1	14	4
Non-service cost components of net periodic benefit income	31	21	93	63
Miscellaneous income	0	3	2	5
Donations	(1)	(1)	(3)	(3)
Miscellaneous expense	(2)	(3)	(6)	(8)
Total Other Income, Net	$ 37	$ 26	$ 115	$ 75