Consolidated Statement of Income (USD $) In Millions, except Per Share data	3 Months Ended				6 Months Ended
	Jun. 30, 2011		Jun. 30, 2010		Jun. 30, 2011		Jun. 30, 2010
Operating Revenues:
Electric	$ 1,614		$ 1,552		$ 3,084		$ 3,007
Gas	167		173		601		658
Total operating revenues	1,781		1,725		3,685		3,665
Operating Expenses:
Fuel	371		286		750		579
Purchased power	237		268		464		539
Gas purchased for resale	79		83		367		416
Other operations and maintenance	475		465		938		902
Depreciation and amortization	194		190		389		377
Taxes other than income taxes	109		102		234		223
Total operating expenses	1,465		1,394		3,142		3,036
Operating Income	316		331		543		629
Other Income and Expenses:
Miscellaneous income	17	[1]	24	[1]	33	[1]	46	[1]
Miscellaneous expense	5	[1]	2	[1]	10	[1]	9	[1]
Total other income	12		22		23		37
Interest charges	104		115		223		247
Income Before Income Taxes	224		238		343		419
Income Taxes	85		83		130		158
Net Income	139	[1]	155	[1]	213	[1]	261	[1]
Less: Net Income Attributable to Noncontrolling Interests	1	[1]	3	[1]	4	[1]	7	[1]
Net Income Attributable to Ameren Corporation	138	[2]	152	[2]	209	[2]	254	[2]
Earnings per Common Share - Basic and Diluted	$ 0.57		$ 0.64		$ 0.87		$ 1.07
Dividends per Common Share	$ 0.385		$ 0.385		$ 0.77		$ 0.77
Average Common Shares Outstanding	241.2		238.4		240.9		238.0
Union Electric Company [Member]
Operating Revenues:
Electric	791		737		1,493		1,344
Gas	28		23		97		98
Other	3		1		4		1
Total operating revenues	822		761		1,594		1,443
Operating Expenses:
Fuel	204		112		433		236
Purchased power	26		42		46		86
Gas purchased for resale	11		10		51		56
Other operations and maintenance	231		240		464		458
Depreciation and amortization	98		92		198		184
Taxes other than income taxes	76		68		149		136
Total operating expenses	646		564		1,341		1,156
Operating Income	176		197		253		287
Other Income and Expenses:
Miscellaneous income	16		20		29		41
Miscellaneous expense	3		1		6		3
Total other income	13		19		23		38
Interest charges	45		43		99		102
Income Before Income Taxes	144		173		177		223
Income Taxes	53		58		64		80
Net Income	91		115		113		143
Preferred Stock Dividends	1		2		2		3
Net Income Available to Common Stockholder	90		113		111		140
Ameren Illinois [Member]
Operating Revenues:
Electric	483		497	[3]	925		998	[3]
Gas	139		150	[3]	505		560	[3]
Other	1				1
Total operating revenues	623		647	[3]	1,431		1,558	[3]
Operating Expenses:
Purchased power	196		227	[3]	407		496	[3]
Gas purchased for resale	67		73	[3]	315		359	[3]
Other operations and maintenance	181		159	[3]	349		321	[3]
Depreciation and amortization	54		52	[3]	106		106	[3]
Taxes other than income taxes	26		24	[3]	67		66	[3]
Total operating expenses	524		535	[3]	1,244		1,348	[3]
Operating Income	99		112	[3]	187		210	[3]
Other Income and Expenses:
Miscellaneous income	1		2	[3]	3		4	[3]
Miscellaneous expense	1		1	[3]	2		4	[3]
Total other income			1	[3]	1
Interest charges	35		34	[3]	70		71	[3]
Income Before Income Taxes	64		79	[3]	118		139	[3]
Income Taxes	26		31	[3]	46		55	[3]
Income from Continuing Operations	38		48	[3]	72		84	[3]
Income from Discontinued Operations, net of tax			9	[3]			21	[3]
Net Income	38		57	[3]	72		105	[3]
Preferred Stock Dividends	1		2	[3]	2		3	[3]
Net Income Available to Common Stockholder	37		55	[3]	70		102	[3]
Ameren Energy Generating Company [Member]
Operating Revenues:
Total operating revenues	260		275		501		542
Operating Expenses:
Fuel	130		136		241		259
Purchased power	18		18		18		20
Other operations and maintenance	45		45		90		94
Depreciation and amortization	25		25		49		49
Taxes other than income taxes	5		6		12		13
Total operating expenses	223		230		410		435
Operating Income	37		45		91		107
Other Income and Expenses:
Miscellaneous income			1				1
Miscellaneous expense							1
Total other income			1
Interest charges	14		20		31		39
Income Before Income Taxes	23		26		60		68
Income Taxes	10		12		25		30
Net Income	13		14		35		38
Less: Net Income Attributable to Noncontrolling Interests			1		1		2
Net Income Attributable to Ameren Corporation	$ 13		$ 13		$ 34		$ 36

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

[2] Represents net income (loss) available to common stockholders.

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