Income Taxes (Schedule Of Components Of Income Tax Expense (Benefit)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Taxes [Line Items]
Current Federal taxes	$ (43)	$ (47)	$ 5
Current State taxes	(1)	1	1
Deferred Federal Income Tax Expense (Benefit)	177	260	194
Deferred State taxes	65	70	80
Amortization of excess deferred income taxes	(112)	(98)	(100)
Amortization of deferred investment tax credits	(3)	(3)	(4)
Income tax benefit	83	183	176
Ameren Missouri
Income Taxes [Line Items]
Current Federal taxes	(55)	(37)	(26)
Current State taxes	(3)	1	(5)
Deferred Federal Income Tax Expense (Benefit)	45	102	93
Deferred State taxes	8	9	18
Amortization of excess deferred income taxes	(79)	(80)	(86)
Amortization of deferred investment tax credits	(3)	(3)	(4)
Income tax benefit	(87)	(8)	(10)
Ameren Illinois
Income Taxes [Line Items]
Current Federal taxes	5	27	46
Current State taxes	0	5	16
Deferred Federal Income Tax Expense (Benefit)	144	123	82
Deferred State taxes	76	71	48
Amortization of excess deferred income taxes	(32)	(17)	(13)
Amortization of deferred investment tax credits	0	0	0
Income tax benefit	193	209	179
Other
Income Taxes [Line Items]
Current Federal taxes	7	(37)	(15)
Current State taxes	2	(5)	(10)
Deferred Federal Income Tax Expense (Benefit)	(12)	35	19
Deferred State taxes	(19)	(10)	14
Amortization of excess deferred income taxes	(1)	(1)	(1)
Amortization of deferred investment tax credits	0	0	0
Income tax benefit	$ (23)	$ (18)	$ 7