Consolidated Statement Of Cash Flows $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Cash Flows From Operating Activities:
Net income	$ 821	$ 529	$ 659
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	938	876	835
Amortization of nuclear fuel	95	76	88
Amortization of debt issuance costs and premium/discounts	20	22	22
Deferred income taxes and investment tax credits, net	224	539	386
Allowance for equity funds used during construction	(36)	(24)	(27)
Share-based Compensation	20	17	17
Other	44	(10)	4
Changes in assets and liabilities:
Receivables	(24)	(53)	(71)
Inventories	39	17	11
Accounts and wages payable	(22)	32	19
Taxes accrued	(10)	55	13
Regulatory assets and liabilities	201	36	215
Assets, other	2	34	(21)
Liabilities, other	(117)	(7)	(17)
Pension and other postretirement benefits	(25)	(21)	(16)
Net cash provided by operating activities	2,170	2,118	2,117
Cash Flows From Investing Activities:
Capital expenditures	(2,286)	(2,132)	(2,076)
Nuclear fuel expenditures	(52)	(63)	(55)
Purchases of securities - nuclear decommissioning trust fund	(315)	(321)	(322)
Sales and maturities of securities - nuclear decommissioning trust fund	299	305	304
Other	18	7	(9)
Net cash used in investing activities	(2,336)	(2,204)	(2,158)
Cash Flows From Financing Activities:
Dividends on common stock	(451)	(431)	(416)
Dividends paid to noncontrolling interest holders	(6)	(6)	(6)
Short-term debt, net	112	(74)	257
Maturities, redemptions, and repurchases of long-term debt	(841)	(681)	(395)
Issuances of Long-term debt	1,352	1,345	396
Proceeds from Issuance of Common Stock	74	0	0
Capital issuance costs	(14)	(11)	(9)
Payments for Repurchase of Common Stock	0	(24)	(51)
Share-based payments	(19)	(15)	(32)
Other	(2)	(1)	(2)
Net cash provided by (used in) financing activities	205	102	(258)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect	39	16	(299)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	107	68	52
Stock Issued	35
Cash Paid (Refunded) During the Year:
Interest net of capitalized	387	370	358
Income taxes, net	21	(19)	(12)
Union Electric Company
Cash Flows From Operating Activities:
Net income	481	326	360
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	533	514	506
Amortization of nuclear fuel	95	76	88
Amortization of debt issuance costs and premium/discounts	6	6	6
Deferred income taxes and investment tax credits, net	(9)	82	179
Allowance for equity funds used during construction	(27)	(21)	(23)
Other	17	4	5
Changes in assets and liabilities:
Receivables	(32)	(46)	5
Inventories	30	18	(4)
Accounts and wages payable	(21)	27	(18)
Taxes accrued	(1)	(1)	11
Regulatory assets and liabilities	201	26	84
Assets, other	2	31	(25)
Liabilities, other	(13)	(23)	(1)
Pension and other postretirement benefits	(2)	(2)	(4)
Net cash provided by operating activities	1,260	1,017	1,169
Cash Flows From Investing Activities:
Capital expenditures	(914)	(773)	(738)
Nuclear fuel expenditures	(52)	(63)	(55)
Purchases of securities - nuclear decommissioning trust fund	(315)	(321)	(322)
Sales and maturities of securities - nuclear decommissioning trust fund	299	305	304
Money pool advances, net		161	(125)
Other	6	7	(1)
Net cash used in investing activities	(976)	(684)	(937)
Cash Flows From Financing Activities:
Dividends on common stock	(375)	(362)	(355)
Dividends on preferred stock	(3)	(3)	(3)
Short-term debt, net	16	39
Maturities, redemptions, and repurchases of long-term debt	(384)	(431)	(266)
Issuances of Long-term debt	423	399	149
Capital issuance costs	(5)	(3)	(3)
Proceeds from Contributions from Parent	45	30	44
Net cash provided by (used in) financing activities	(283)	(331)	(434)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect	1	2	(202)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	8	7	5
Cash Paid (Refunded) During the Year:
Interest net of capitalized	196	202	209
Income taxes, net	128	178	27
Ameren Illinois Company
Cash Flows From Operating Activities:
Net income	307	271	255
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	375	341	318
Amortization of debt issuance costs and premium/discounts	13	13	14
Deferred income taxes and investment tax credits, net	88	171	154
Allowance for equity funds used during construction	(9)	(3)	(4)
Other	11	0	(1)
Changes in assets and liabilities:
Receivables	0	(7)	(72)
Inventories	8	(1)	15
Accounts and wages payable	(13)	19	12
Taxes accrued	(13)	18	1
Regulatory assets and liabilities	1	16	120
Assets, other	(1)	(2)	(3)
Liabilities, other	(92)	3	(9)
Pension and other postretirement benefits	(25)	(14)	(8)
Net cash provided by operating activities	659	828	796
Cash Flows From Investing Activities:
Capital expenditures	(1,258)	(1,076)	(924)
Other	10	6	6
Net cash used in investing activities	(1,248)	(1,070)	(918)
Cash Flows From Financing Activities:
Dividends on common stock	0	0	(110)
Dividends on preferred stock	(3)	(3)	(3)
Short-term debt, net	10	11	51
Maturities, redemptions, and repurchases of long-term debt	(457)	(250)	(129)
Issuances of Long-term debt	929	496	247
Capital issuance costs	(9)	(6)	(4)
Proceeds from Contributions from Parent	160	8	0
Other	(2)	(1)	(1)
Net cash provided by (used in) financing activities	628	255	51
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect	39	13	(71)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	80	41	28
Cash Paid (Refunded) During the Year:
Interest net of capitalized	144	139	127
Income taxes, net	$ 28	$ (22)	$ 8