Consolidated Statement of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash Flows From Operating Activities:
Net income	$ 752	$ 588
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	699	653
Amortization of nuclear fuel	71	71
Amortization of debt issuance costs and premium/discounts	16	16
Deferred income taxes and investment tax credits, net	212	366
Allowance for equity funds used during construction	(25)	(16)
Stock-based compensation costs	15	12
Other	21	(7)
Changes in assets and liabilities:
Receivables	(129)	(59)
Inventories	(4)	(20)
Accounts and wages payable	(198)	(183)
Taxes accrued	92	138
Regulatory assets and liabilities	213	89
Assets, other	(2)	18
Liabilities, other	(45)	12
Pension and other postretirement benefits	(2)	(31)
Net cash provided by operating activities	1,686	1,647
Cash Flows From Investing Activities:
Capital expenditures	(1,689)	(1,523)
Nuclear fuel expenditures	(30)	(52)
Payments to Acquire Investments to be Held in Decommissioning Trust Fund	(172)	(187)
Proceeds from Decommissioning Trust Fund Assets	159	175
Other	13	3
Net cash used in investing activities	(1,719)	(1,584)
Cash Flows From Financing Activities:
Dividends on common stock	(334)	(320)
Dividends paid to noncontrolling interest holders	(5)	(5)
Short-term debt, net	36	(112)
Repayments of Long-term Debt	(522)	(425)
Proceeds from Issuance of Long-term Debt	853	849
Issuance of common stock	56	0
Repurchases of common stock for stock-based compensation	0	(24)
Employee payroll taxes related to stock-based compensation	(19)	(15)
Payment of Financing and Stock Issuance Costs	(9)	(5)
Other	1	(1)
Net cash provided by (used in) financing activities	57	(58)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect	24	5
Noncash financing activity - Issuance of common stock for stock-based compensation	35	0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	92	57
Union Electric Company
Cash Flows From Operating Activities:
Net income	503	362
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	398	384
Amortization of nuclear fuel	71	71
Amortization of debt issuance costs and premium/discounts	4	5
Deferred income taxes and investment tax credits, net	4	55
Allowance for equity funds used during construction	(19)	(15)
Other	14	4
Changes in assets and liabilities:
Receivables	(156)	(117)
Inventories	3	(3)
Accounts and wages payable	(168)	(151)
Taxes accrued	148	160
Regulatory assets and liabilities	149	48
Assets, other	0	19
Liabilities, other	7	4
Pension and other postretirement benefits	3	(7)
Net cash provided by operating activities	961	819
Cash Flows From Investing Activities:
Capital expenditures	(664)	(533)
Nuclear fuel expenditures	(30)	(52)
Payments to Acquire Investments to be Held in Decommissioning Trust Fund	(172)	(187)
Proceeds from Decommissioning Trust Fund Assets	159	175
Money pool advances, net	(28)	143
Net cash used in investing activities	(735)	(454)
Cash Flows From Financing Activities:
Dividends on common stock	(225)	(332)
Dividends on preferred stock	(3)	(3)
Short-term debt, net	(39)
Repayments of Long-term Debt	(378)	(425)
Proceeds from Issuance of Long-term Debt	423	399
Payment of Financing and Stock Issuance Costs	(4)	(3)
Net cash provided by (used in) financing activities	(226)	(364)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect	0	1
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	7	6
Ameren Illinois Company
Cash Flows From Operating Activities:
Net income	222	193
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	278	254
Amortization of debt issuance costs and premium/discounts	10	10
Deferred income taxes and investment tax credits, net	56	161
Allowance for equity funds used during construction	(6)	(1)
Other	5	(1)
Changes in assets and liabilities:
Receivables	21	59
Inventories	(7)	(17)
Accounts and wages payable	(44)	(24)
Taxes accrued	(40)	(22)
Regulatory assets and liabilities	63	45
Assets, other	0	(5)
Liabilities, other	(40)	(2)
Pension and other postretirement benefits	(8)	(19)
Net cash provided by operating activities	516	632
Cash Flows From Investing Activities:
Capital expenditures	(947)	(760)
Other	10	6
Net cash used in investing activities	(937)	(754)
Cash Flows From Financing Activities:
Dividends on preferred stock	(2)	(2)
Short-term debt, net	46	118
Proceeds from (Repayments of) Short-term Debt, Maturing in More than Three Months	45	11
Repayments of Long-term Debt	(144)	0
Proceeds from Issuance of Long-term Debt	430
Payment of Financing and Stock Issuance Costs	(5)
Capital contribution from parent	80
Other	1	(1)
Net cash provided by (used in) financing activities	451	126
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect	30	4
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 71	$ 32