Consolidated Statement of Cash Flows (USD $) In Millions	6 Months Ended
	Jun. 30, 2011		Jun. 30, 2010
Cash Flows From Operating Activities:
Net income	$ 213	[1]	$ 261	[1]
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sales of properties	(11)		(5)
Net mark-to-market (gain) loss on derivatives	(5)
Depreciation and amortization	391		387
Amortization of nuclear fuel	34		19
Amortization of debt issuance costs and premium/discounts	12		12
Deferred income taxes and investment tax credits, net	221		175
Allowance for equity funds used during construction	(15)	[1]	(26)	[1]
Other	10		5
Changes in assets and liabilities:
Receivables	(55)		(36)
Materials and supplies	55		108
Accounts and wages payable	(133)		(125)
Taxes accrued	76		75
Assets, other	60		(99)
Liabilities, other	(3)
Pension and other postretirement benefits	31		33
Counterparty collateral, net	23		(69)
Taum Sauk insurance recoveries, net of costs	(1)		56
Net cash provided by operating activities	903		771
Cash Flows From Investing Activities:
Capital expenditures	(507)		(547)
Nuclear fuel expenditures	(33)		(22)
Purchases of securities - nuclear decommissioning trust fund	(125)		(118)
Sales of securities - nuclear decommissioning trust fund	113		110
Proceeds from sales of properties	49		20
Other	5		(3)
Net cash used in investing activities	(498)		(560)
Cash Flows From Financing Activities:
Dividends on common stock	(186)		(183)
Dividends paid to noncontrolling interest holders	(3)		(5)
Short-term and credit facility repayments, net	(192)		(160)
Maturities of long-term debt	(150)
Issuances of common stock	32		43
Generator advances for construction refunded, net of receipts	(73)		(22)
Net cash used in financing activities	(572)		(327)
Net change in cash and cash equivalents	(167)		(116)
Cash and cash equivalents at beginning of year	545		622
Cash and cash equivalents at end of period	378		506
Noncash investing activity - DOE Settlement (Note 10)	9
Union Electric Company [Member]
Cash Flows From Operating Activities:
Net income	113		143
Adjustments to reconcile net income to net cash provided by operating activities:
Net mark-to-market (gain) loss on derivatives	1
Depreciation and amortization	198		184
Amortization of nuclear fuel	34		19
Amortization of debt issuance costs and premium/discounts	3
Deferred income taxes and investment tax credits, net	86		106
Allowance for equity funds used during construction	(14)		(25)
Other			(2)
Changes in assets and liabilities:
Receivables	(82)		(97)
Materials and supplies	(2)		22
Accounts and wages payable	(136)		(158)
Taxes accrued	58		125
Assets, other	57		(137)
Liabilities, other	23		39
Pension and other postretirement benefits	15		12
Taum Sauk insurance recoveries, net of costs	(1)		56
Net cash provided by operating activities	353		287
Cash Flows From Investing Activities:
Capital expenditures	(272)		(321)
Nuclear fuel expenditures	(33)		(22)
Purchases of securities - nuclear decommissioning trust fund	(125)		(118)
Sales of securities - nuclear decommissioning trust fund	113		110
Other	(3)
Net cash used in investing activities	(320)		(351)
Cash Flows From Financing Activities:
Dividends on common stock	(135)		(116)
Dividends on preferred stock	(2)		(3)
Generator advances for construction refunded, net of receipts	(19)		7
Net cash used in financing activities	(156)		(112)
Net change in cash and cash equivalents	(123)		(176)
Cash and cash equivalents at beginning of year	202		267
Cash and cash equivalents at end of period	79		91
Noncash investing activity - DOE Settlement (Note 10)	9
Ameren Illinois [Member]
Cash Flows From Operating Activities:
Net income	72		105	[2]
Income from discontinued operations, net of tax			(21)	[2]
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	106		106	[2]
Amortization of debt issuance costs and premium/discounts	4		5	[2]
Deferred income taxes and investment tax credits, net	86		34	[2]
Other	(1)		(1)	[2]
Changes in assets and liabilities:
Receivables	45		68	[2]
Materials and supplies	53		60	[2]
Accounts and wages payable	(3)		(32)	[2]
Taxes accrued	21		5	[2]
Assets, other	32		(28)	[2]
Liabilities, other	(24)		(27)	[2]
Pension and other postretirement benefits	14		12	[2]
Operating cash flows provided by discontinued operations			46	[2]
Net cash provided by operating activities	405		332	[2]
Cash Flows From Investing Activities:
Capital expenditures	(174)		(147)	[2]
Returns from (advances to) ATXI for construction	49		(6)	[2]
Proceeds from intercompany note receivable - Genco			45	[2]
Net investing activities used in discontinued operations			(3)	[2]
Net cash used in investing activities	(125)		(111)	[2]
Cash Flows From Financing Activities:
Dividends on common stock	(150)		(67)	[2]
Dividends on preferred stock	(2)		(3)	[2]
Maturities of long-term debt	(150)
Generator advances for construction refunded, net of receipts	(53)		(29)	[2]
Net financing activities used in discontinued operations			(45)	[2]
Capital contribution from parent	6
Net cash used in financing activities	(349)		(144)	[2]
Net change in cash and cash equivalents	(69)		77	[2]
Cash and cash equivalents at beginning of year	322		306	[2]
Cash and cash equivalents at end of period	253		383	[2]
Noncash investing activity - asset transfer from ATXI			1	[2]
Ameren Energy Generating Company [Member]
Cash Flows From Operating Activities:
Net income	35		38
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sales of properties	(11)		(5)
Net mark-to-market (gain) loss on derivatives	(6)		4
Depreciation and amortization	51		56
Amortization of debt issuance costs and premium/discounts	1		2
Deferred income taxes and investment tax credits, net	39		31
Other	1
Changes in assets and liabilities:
Receivables	(28)		4
Materials and supplies	9		17
Accounts and wages payable	13		(11)
Taxes accrued	1		20
Assets, other	(2)		5
Liabilities, other	(12)		(17)
Pension and other postretirement benefits	(3)		3
Net cash provided by operating activities	88		147
Cash Flows From Investing Activities:
Capital expenditures	(84)		(59)
Proceeds from sales of properties	48		18
Money pool advances, net	25		(21)
Net cash used in investing activities	(11)		(62)
Cash Flows From Financing Activities:
Short-term and credit facility repayments, net	(100)
Note payable - affiliates			(84)
Capital contribution from parent	24
Net cash used in financing activities	(76)		(84)
Net change in cash and cash equivalents	1		1
Cash and cash equivalents at beginning of year	6		6
Cash and cash equivalents at end of period	$ 7		$ 7

[1] Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.

[2] Prior period reflects the Ameren Illinois Merger as discussed in Note 1 - Summary of Significant Accounting Policies.