Consolidated Statement of Income (Loss) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Operating Revenues:
Electric	$ 1,507		$ 1,579		$ 3,823		$ 3,898
Gas	131		130		693		625
Total operating revenues	1,638		1,709		4,516		4,523
Operating Expenses:
Fuel	222		194		648		550
Purchased power	128		260		400		630
Gas purchased for resale	42		40		344		304
Other operations and maintenance	383		362		1,229		1,126
Depreciation and amortization	175		161		528		496
Taxes other than income taxes	121		114		354		337
Total operating expenses	1,071		1,131		3,503		3,443
Operating Income	567		578		1,013		1,080
Other Income and Expenses:
Miscellaneous income	20	[1]	17	[1]	51	[1]	53	[1]
Miscellaneous expense	5	[1]	6	[1]	18	[1]	28	[1]
Total other income (expense)	15		11		33		25
Interest Charges	88		99		289		295
Income Before Income Taxes	494		490		757		810
Income Taxes	187		179		288		298
Income from Continuing Operations	307		311		469		512
Income (Loss) from Discontinued Operations, Net of Taxes (Note 2)	(3)		63		(212)		(331)
Net Income	304		374		257		181
Pension and other postretirement benefit plan activity, net of income taxes (benefit)	(5)		0		5		1
Comprehensive Income (Loss)	292		406		241		234
Less: Net Income (Loss) Attributable to Noncontrolling Interests:
Continuing Operations	2		2		5		5
Discontinued Operations			(2)				(6)
Net Income (Loss):
Continuing Operations	305		309		464		507
Discontinued Operations	(3)		65		(212)		(325)
Net Income (Loss)	302		374		252		182
Earnings (Loss) per Common Share – Basic
Continuing Operations - Basic	$ 1.26		$ 1.28		$ 1.92		$ 2.09
Discontinued Operations - Basic	$ (0.01)		$ 0.26		$ (0.88)		$ (1.34)
Earnings per Common Share - Basic	$ 1.25		$ 1.54		$ 1.04		$ 0.75
Earnings (Loss) per Common Stock - Diluted
Continuing Operations - Diluted	$ 1.25		$ 1.28		$ 1.91		$ 2.09
Discontinued Operations - Diluted	$ (0.01)		$ 0.26		$ (0.88)		$ (1.34)
Earnings per Common Share - Diluted	$ 1.24		$ 1.54		$ 1.03		$ 0.75
Dividends per Common Share	$ 0.40		$ 0.40		$ 1.20		$ 1.20
Average Common Shares Outstanding - Basic	242.6		242.6		242.6		242.6
Average Common Shares Outstanding - Diluted	245.1		242.9		244.4		242.9
Union Electric Company
Operating Revenues:
Electric	1,075		1,046		2,667		2,504
Gas	17		18		110		94
Other	1.0				1.0		1.0
Total operating revenues	1,093		1,064		2,778		2,599
Operating Expenses:
Fuel	222		192		648		549
Purchased power	33		37		100		57
Gas purchased for resale	4		5		52		42
Other operations and maintenance	212		203		686		611
Depreciation and amortization	114		111		338		328
Taxes other than income taxes	91		87		247		236
Total operating expenses	676		635		2,071		1,823
Operating Income	417		429		707		776
Other Income and Expenses:
Miscellaneous income	16		15		44		48
Miscellaneous expense	2		4		10		11
Total other income (expense)	14		11		34		37
Interest Charges	43		55		159		167
Income Before Income Taxes	388		385		582		646
Income Taxes	149		148		217		243
Net Income	239		237		365		403
Other Comprehensive Income	0		0		0		0
Comprehensive Income (Loss)	239		237		365		403
Net Income (Loss):
Net Income (Loss)	239		237		365		403
Earnings (Loss) per Common Stock - Diluted
Preferred Stock Dividends	1		1		3		3
Net Income Available to Common Stockholder	238		236		362		400
Ameren Illinois Company
Operating Revenues:
Electric	432		536		1,160		1,404
Gas	115		112		585		532
Other					2.0
Total operating revenues	547		648		1,747		1,936
Operating Expenses:
Purchased power	96		224		303		576
Gas purchased for resale	38		35		292		262
Other operations and maintenance	166		159		538		513
Depreciation and amortization	59		55		182		165
Taxes other than income taxes	30		24		102		94
Total operating expenses	389		497		1,417		1,610
Operating Income	158		151		330		326
Other Income and Expenses:
Miscellaneous income	4		2		7		5
Miscellaneous expense	3		2		7		15
Total other income (expense)	1						(10)
Interest Charges	31		34		96		98
Income Before Income Taxes	128		117		234		218
Income Taxes	51		46		93		86
Net Income	77		71		141		132
Pension and other postretirement benefit plan activity, net of income taxes (benefit)			(1)		(2)		(3)
Comprehensive Income (Loss)	77		70		139		129
Net Income (Loss):
Net Income (Loss)	77		71		141		132
Earnings (Loss) per Common Stock - Diluted
Preferred Stock Dividends					2		2
Net Income Available to Common Stockholder	$ 77		$ 71		$ 139		$ 130

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