Consolidated Statement Of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash Flows From Operating Activities:
Net income	$ 1,079	$ 995	$ 877
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,438	1,277	1,153
Amortization of debt issuance costs and premium/discounts	21	23	22
Deferred income taxes and investment tax credits, net	170	156	148
Allowance for equity funds used during construction	(43)	(43)	(32)
Stock-based compensation costs	24	22	21
Other	68	19	22
Changes in assets and liabilities:
Receivables	(317)	(74)	(47)
Inventories	(77)	(71)	(25)
Accounts and wages payable	136	28	40
Taxes accrued	(13)	1	34
Regulatory assets and liabilities	(72)	(439)	(254)
Assets, other	(74)	(71)	(74)
Liabilities, other	52	(75)	(110)
Pension and other postretirement benefits	(65)	(33)	(38)
Counterparty collateral, net	(64)	(54)	(10)
Net cash provided by operating activities	2,263	1,661	1,727
Cash Flows From Investing Activities:
Capital expenditures	(3,351)	(3,479)	(3,233)
Nuclear fuel expenditures	(29)	(44)	(66)
Purchases of securities – nuclear decommissioning trust fund	(229)	(452)	(224)
Proceeds from sales and maturities	216	439	183
Other	23	8	11
Net cash used in investing activities	(3,370)	(3,528)	(3,329)
Cash Flows From Financing Activities:
Dividends on common stock	(610)	(565)	(494)
Dividends paid to noncontrolling interest holders	(5)	(5)	(6)
Short-term debt, net	522	55	50
Maturities of long-term debt	(505)	(8)	(442)
Issuances of long-term debt	1,467	1,997	2,183
Issuances of common stock	333	308	476
Redemptions of Ameren Illinois preferred stock	0	(13)	0
Employee payroll taxes related to stock-based compensation	(16)	(17)	(20)
Debt issuance costs	(18)	(18)	(20)
Other	0	(13)	0
Net cash provided by financing activities	1,168	1,721	1,727
Net change in cash, cash equivalents, and restricted cash	61	(146)	125
Cash, cash equivalents, and restricted cash at beginning of year	155	301	176
Cash, cash equivalents, and restricted cash at end of year	216	155	301
Cash Paid (Refunded) During the Year:
Interest (net of amounts capitalized, respectively)	476	426	383
Income taxes, net	(8)	(1)	13
Union Electric Company
Cash Flows From Operating Activities:
Net income	565	521	439
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	881	762	681
Amortization of debt issuance costs and premium/discounts	7	6	6
Deferred income taxes and investment tax credits, net	21	3	17
Allowance for equity funds used during construction	(24)	(26)	(19)
Other	14	19	22
Changes in assets and liabilities:
Receivables	(68)	(60)	(8)
Inventories	(15)	(32)	(11)
Accounts and wages payable	19	28	26
Taxes accrued	(21)	(27)	9
Regulatory assets and liabilities	(206)	(207)	(166)
Assets, other	(34)	(27)	(2)
Liabilities, other	7	(29)	(80)
Pension and other postretirement benefits	(16)	(2)	(3)
Net cash provided by operating activities	1,130	929	911
Cash Flows From Investing Activities:
Capital expenditures	(1,690)	(2,015)	(1,666)
Nuclear fuel expenditures	(29)	(44)	(66)
Purchases of securities – nuclear decommissioning trust fund	(229)	(452)	(224)
Proceeds from sales and maturities	216	439	183
Money pool advances, net	0	139
Money pool advances, net			(139)
Other	29	11	8
Net cash used in investing activities	(1,703)	(1,922)	(1,904)
Cash Flows From Financing Activities:
Dividends on common stock	(46)	(24)	(66)
Dividends on preferred stock	(3)	(3)	(3)
Short-term debt, net	164	165	(234)
Maturities of long-term debt	(55)	(8)	(92)
Issuances of long-term debt	524	524	1,012
Debt issuance costs	(6)	(5)	(9)
Capital contribution from parent	0	207	491
Net cash provided by financing activities	578	856	1,099
Net change in cash, cash equivalents, and restricted cash	5	(137)	106
Cash, cash equivalents, and restricted cash at beginning of year	8	145	39
Cash, cash equivalents, and restricted cash at end of year	13	8	145
Cash Paid (Refunded) During the Year:
Interest (net of amounts capitalized, respectively)	230	205	190
Income taxes, net	(20)	19	25
Ameren Illinois Company
Cash Flows From Operating Activities:
Net income	515	427	382
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	514	471	434
Amortization of debt issuance costs and premium/discounts	11	13	12
Deferred income taxes and investment tax credits, net	117	165	118
Allowance for equity funds used during construction	(18)	(17)	(13)
Other	29	10	21
Changes in assets and liabilities:
Receivables	(250)	(17)	(28)
Inventories	(62)	(40)	(15)
Accounts and wages payable	117	2	15
Taxes accrued	34	22	(23)
Regulatory assets and liabilities	134	(222)	(72)
Assets, other	(107)	(75)	(76)
Liabilities, other	53	(45)	(46)
Pension and other postretirement benefits	(39)	(32)	(30)
Net cash provided by operating activities	1,048	662	679
Cash Flows From Investing Activities:
Capital expenditures	(1,601)	(1,432)	(1,447)
Other	(1)	(5)	3
Net cash used in investing activities	(1,602)	(1,437)	(1,444)
Cash Flows From Financing Activities:
Dividends on common stock	0	0	(9)
Dividends on preferred stock	(2)	(2)	(3)
Short-term debt, net	161	103	(53)
Money pool borrowings, net	0	(19)	19
Maturities of long-term debt	(400)	0	0
Issuances of long-term debt	848	449	373
Redemption of preferred stock	0	(13)	0
Debt issuance costs	(10)	(6)	(4)
Capital contribution from parent	15	262	464
Other	0	(13)	0
Net cash provided by financing activities	612	761	787
Net change in cash, cash equivalents, and restricted cash	58	(14)	22
Cash, cash equivalents, and restricted cash at beginning of year	133	147	125
Cash, cash equivalents, and restricted cash at end of year	191	133	147
Cash Paid (Refunded) During the Year:
Interest (net of amounts capitalized, respectively)	152	148	137
Income taxes, net	$ 23	$ (41)	$ 41