Consolidated Statement Of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash Flows From Operating Activities:
Net income	$ 1,157	$ 1,079	$ 995
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,432	1,373	1,219
Amortization of nuclear fuel	68	65	58
Amortization of debt issuance costs and premium/discounts	16	21	23
Deferred income taxes and investment tax credits, net	229	170	156
Allowance for equity funds used during construction	(54)	(43)	(43)
Stock-based compensation costs	26	24	22
Other	16	68	19
Changes in assets and liabilities:
Receivables	144	(317)	(74)
Inventories	(67)	(77)	(71)
Accounts and wages payable	(104)	136	28
Taxes accrued	(4)	(13)	1
Regulatory assets and liabilities	(165)	(72)	(439)
Assets, other	(109)	(74)	(71)
Liabilities, other	115	52	(75)
Pension and other postretirement benefits	(283)	(65)	(33)
Counterparty collateral, net	147	(64)	(54)
Net cash provided by operating activities	2,564	2,263	1,661
Cash Flows From Investing Activities:
Capital expenditures	(3,597)	(3,351)	(3,479)
Nuclear fuel expenditures	(174)	(29)	(44)
Purchases of securities – nuclear decommissioning trust fund	(266)	(229)	(452)
Proceeds from sales and maturities	240	216	439
Other	(1)	23	8
Net cash used in investing activities	(3,798)	(3,370)	(3,528)
Cash Flows From Financing Activities:
Dividends on common stock	(662)	(610)	(565)
Dividends paid to noncontrolling interest holders	(5)	(5)	(5)
Short-term debt, net	(533)	522	55
Maturities of long-term debt	(100)	(505)	(8)
Issuances of long-term debt	2,295	1,467	1,997
Issuances of common stock	346	333	308
Redemptions of Ameren Illinois preferred stock	0	0	(13)
Employee payroll taxes related to stock-based compensation	(20)	(16)	(17)
Debt issuance costs	(21)	(18)	(18)
Other	(10)	0	(13)
Net cash provided by financing activities	1,290	1,168	1,721
Net change in cash, cash equivalents, and restricted cash	56	61	(146)
Cash, cash equivalents, and restricted cash at beginning of year	216	155	301
Cash Paid (Refunded) During the Year:
Interest (net of amounts capitalized, respectively)	546	476	426
Income Taxes Paid, Net	(24)	(8)	(1)
Ameren Missouri
Cash Flows From Operating Activities:
Net income	548	565	521
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	827	816	704
Amortization of nuclear fuel	68	65	58
Amortization of debt issuance costs and premium/discounts	7	7	6
Deferred income taxes and investment tax credits, net	28	21	3
Allowance for equity funds used during construction	(30)	(24)	(26)
Other	(8)	14	19
Changes in assets and liabilities:
Receivables	39	(68)	(60)
Inventories	(74)	(15)	(32)
Accounts and wages payable	(8)	19	28
Taxes accrued	(17)	(21)	(27)
Regulatory assets and liabilities	(7)	(206)	(207)
Assets, other	(25)	1	28
Liabilities, other	3	7	(29)
Pension and other postretirement benefits	(106)	(16)	(2)
Counterparty collateral, net	96	(35)	(55)
Net cash provided by operating activities	1,341	1,130	929
Cash Flows From Investing Activities:
Capital expenditures	(1,760)	(1,690)	(2,015)
Nuclear fuel expenditures	(174)	(29)	(44)
Purchases of securities – nuclear decommissioning trust fund	(266)	(229)	(452)
Proceeds from sales and maturities	240	216	439
Money pool advances, net	0	0	139
Other	0	29	11
Net cash used in investing activities	(1,960)	(1,703)	(1,922)
Cash Flows From Financing Activities:
Dividends on common stock	(9)	(46)	(24)
Dividends on preferred stock	(3)	(3)	(3)
Short-term debt, net	(159)	164	165
Money pool borrowings, net	306	0	0
Maturities of long-term debt	0	(55)	(8)
Issuances of long-term debt	499	524	524
Debt issuance costs	(8)	(6)	(5)
Capital contribution from parent	0	0	207
Other	(10)	0	0
Net cash provided by financing activities	616	578	856
Net change in cash, cash equivalents, and restricted cash	(3)	5	(137)
Cash, cash equivalents, and restricted cash at beginning of year	13	8	145
Cash Paid (Refunded) During the Year:
Interest (net of amounts capitalized, respectively)	225	230	205
Income Taxes Paid, Net	(19)	(20)	19
Ameren Illinois
Cash Flows From Operating Activities:
Net income	609	515	427
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	557	514	471
Amortization of debt issuance costs and premium/discounts	5	11	13
Deferred income taxes and investment tax credits, net	177	117	165
Allowance for equity funds used during construction	(19)	(18)	(17)
Other	40	29	10
Changes in assets and liabilities:
Receivables	129	(250)	(17)
Inventories	7	(62)	(40)
Accounts and wages payable	(107)	117	2
Taxes accrued	(73)	34	22
Regulatory assets and liabilities	(152)	134	(222)
Assets, other	(123)	(67)	(75)
Liabilities, other	106	42	(46)
Pension and other postretirement benefits	(112)	(39)	(32)
Counterparty collateral, net	54	(29)	1
Net cash provided by operating activities	1,098	1,048	662
Cash Flows From Investing Activities:
Capital expenditures	(1,731)	(1,601)	(1,432)
Other	(2)	(1)	(5)
Net cash used in investing activities	(1,733)	(1,602)	(1,437)
Cash Flows From Financing Activities:
Dividends on common stock	(41)	0	0
Dividends on preferred stock	(2)	(2)	(2)
Short-term debt, net	102	161	103
Money pool borrowings, net	135	0	(19)
Maturities of long-term debt	(100)	(400)	0
Issuances of long-term debt	498	848	449
Redemption of preferred stock	0	0	(13)
Debt issuance costs	(5)	(10)	(6)
Capital contribution from parent	91	15	262
Other	0	0	(13)
Net cash provided by financing activities	678	612	761
Net change in cash, cash equivalents, and restricted cash	43	58	(14)
Cash, cash equivalents, and restricted cash at beginning of year	191	133	147
Cash Paid (Refunded) During the Year:
Interest (net of amounts capitalized, respectively)	195	152	148
Income Taxes Paid, Net	$ 102	$ 23	$ (41)