Other Income, Net (Other Income And Expenses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Other Nonoperating Income (Expense) [Line Items]
Allowance for equity funds used during construction	$ 43	$ 43	$ 32
Interest income on industrial development revenue bonds	24	25	25
Other interest income	11	2	4
Non-service cost components of net periodic benefit income	184	136	116
Miscellaneous income	10	10	10
Equity in earnings of subsidiaries	2	12	3
Donations	(26)	(9)	(25)
Miscellaneous expense	(22)	(17)	(14)
Total other income, net	226	202	151
Union Electric Company
Other Nonoperating Income (Expense) [Line Items]
Allowance for equity funds used during construction	24	26	19
Interest income on industrial development revenue bonds	24	25	25
Other interest income	4	1	1
Non-service cost components of net periodic benefit income	55	55	46
Miscellaneous income	4	3	4
Donations	(3)	(4)	(12)
Miscellaneous expense	(9)	(7)	(7)
Total other income, net	99	99	76
Defined Benefit Plan, Non-service Cost or Income Components - Tracker	22	(7)	(4)
Union Electric Company | Final Rate Order | Electric
Other Nonoperating Income (Expense) [Line Items]
Donations		(8)
Ameren Illinois Company
Other Nonoperating Income (Expense) [Line Items]
Allowance for equity funds used during construction	18	17	13
Other interest income	7	1	3
Non-service cost components of net periodic benefit income	84	55	48
Miscellaneous income	5	6	6
Donations	(8)	(5)	(5)
Miscellaneous expense	(10)	(8)	(6)
Total other income, net	$ 96	$ 66	$ 59