Consolidated Statement of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash Flows From Operating Activities:
Net income	$ 393	$ 298
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	463	433
Amortization of nuclear fuel	48	48
Amortization of debt issuance costs and premium/discounts	11	11
Deferred income taxes and investment tax credits, net	81	175
Allowance for equity funds used during construction	(14)	(10)
Stock-based compensation costs	10	8
Other	11	(5)
Changes in assets and liabilities:
Receivables	(170)	(54)
Inventories	46	14
Accounts and wages payable	(209)	(183)
Taxes accrued	105	83
Regulatory assets and liabilities	83	(4)
Assets, other	8	22
Liabilities, other	(50)	21
Pension and other postretirement benefits	4	6
Net cash provided by operating activities	820	863
Cash Flows From Investing Activities:
Capital expenditures	(1,112)	(998)
Nuclear fuel expenditures	(16)	(50)
Payments to Acquire Investments to be Held in Decommissioning Trust Fund	(129)	(161)
Proceeds from Decommissioning Trust Fund Assets	122	152
Other	6	(2)
Net cash used in investing activities	(1,129)	(1,059)
Cash Flows From Financing Activities:
Dividends on common stock	(223)	(214)
Dividends paid to noncontrolling interest holders	(3)	(3)
Short-term debt, net	21	334
Repayments of Long-term Debt	(323)	(425)
Proceeds from Issuance of Long-term Debt	853	549
Issuance of common stock	40	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)	(4)
Other	0	(1)
Net cash provided by financing activities	337	197
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect	28	1
Noncash financing activity - Issuance of common stock for stock-based compensation	35	0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	96	53
Union Electric Company
Cash Flows From Operating Activities:
Net income	208	127
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	265	255
Amortization of nuclear fuel	48	48
Amortization of debt issuance costs and premium/discounts	3	3
Deferred income taxes and investment tax credits, net	(24)	13
Allowance for equity funds used during construction	(11)	(9)
Other	10	3
Changes in assets and liabilities:
Receivables	(205)	(124)
Inventories	8	(7)
Accounts and wages payable	(160)	(169)
Taxes accrued	152	153
Regulatory assets and liabilities	106	57
Assets, other	(2)	19
Liabilities, other	11	24
Pension and other postretirement benefits	3	3
Net cash provided by operating activities	412	396
Cash Flows From Investing Activities:
Capital expenditures	(454)	(355)
Nuclear fuel expenditures	(16)	(50)
Payments to Acquire Investments to be Held in Decommissioning Trust Fund	(129)	(161)
Proceeds from Decommissioning Trust Fund Assets	122	152
Money pool advances, net	(66)	161
Net cash used in investing activities	(543)	(253)
Cash Flows From Financing Activities:
Dividends on common stock	(50)	(172)
Dividends on preferred stock	(2)	(2)
Short-term debt, net	(39)	60
Repayments of Long-term Debt	(179)	(425)
Proceeds from Issuance of Long-term Debt	423	399
Payment of Financing and Stock Issuance Costs	(4)	(3)
Net cash provided by financing activities	149	(143)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect	18	0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	25	5
Ameren Illinois Company
Cash Flows From Operating Activities:
Net income	159	138
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	184	168
Amortization of debt issuance costs and premium/discounts	7	7
Deferred income taxes and investment tax credits, net	13	116
Allowance for equity funds used during construction	(3)	(1)
Other	(3)	0
Changes in assets and liabilities:
Receivables	23	70
Inventories	38	20
Accounts and wages payable	(35)	(17)
Taxes accrued	(23)	(68)
Regulatory assets and liabilities	(20)	(54)
Assets, other	4	3
Liabilities, other	(58)	(10)
Pension and other postretirement benefits	(2)	2
Net cash provided by operating activities	287	375
Cash Flows From Investing Activities:
Capital expenditures	(602)	(484)
Other	3	4
Net cash used in investing activities	(599)	(480)
Cash Flows From Financing Activities:
Dividends on preferred stock	(2)	(2)
Short-term debt, net	(62)	108
Proceeds from (Repayments of) Short-term Debt, Maturing in More than Three Months	31
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	0	(1)
Net cash provided by financing activities	328	105
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect	16	0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 57	$ 28