Consolidated Statement Of Income (Loss) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Operating Revenues:
Electric	$ 4,913		$ 4,832		$ 4,857
Gas	1,140		1,006		924
Total operating revenues	6,053		5,838		5,781
Operating Expenses:
Fuel	826		845		714
Purchased power	454		502		780
Gas purchased for resale	615		526		472
Other operations and maintenance	1,691		1,617		1,511
Depreciation and amortization	745		706		673
Taxes other than income taxes	468		458		443
Total operating expenses	4,799		4,654		4,593
Operating Income	1,254		1,184		1,188
Other Income and Expenses:
Miscellaneous income	79	[1]	69	[1]	70	[1]
Miscellaneous expense	22	[1]	26	[1]	37	[1]
Total other income (expense)	57		43		33
Interest charges	341		398		392
Income Before Income Taxes	970		829		829
Income taxes	377		311		307
Income from Continuing Operations	593		518		522
Income (Loss) from Discontinued Operations, Net of Tax (Note 16)	(1)		(223)		(1,496)
Net Income (Loss)	592		295		(974)
Less: Net Income (Loss) Attributable to Noncontrolling Interests:
Continuing Operations	6		6		6
Discontinued Operations					(6)
Net Income (Loss):
Net income attributable to Ameren Corporation - continuing operations	587		512		516
Discontinued Operations	(1)		(223)		(1,490)
Net income (loss) attributable to Ameren Corporation	586		289		(974)
Pension and other postretirement activity, net of income taxes (benefit)	(12)		30		(8)
Comprehensive Income (Loss)	574		300		(932)
Earnings (Loss) per Common Share – Basic:
Continuing Operations - Basic	$ 2.42		$ 2.11		$ 2.13
Discontinued Operations - Basic	$ 0.00		$ (0.92)		$ (6.14)
Earnings (Loss) per Common Share – Basic	$ 2.42		$ 1.19		$ (4.01)
Earnings (Loss) per Common Share – Diluted:
Continuing Operations - Diluted	$ 2.40		$ 2.10		$ 2.13
Discontinued Operations - Diluted	$ 0.00		$ (0.92)		$ (6.14)
Earnings (Loss) per Common Share – Diluted	$ 2.40		$ 1.18		$ (4.01)
Dividends per Common Share	$ 1.61		$ 1.60		$ 1.600
Average Common Shares Outstanding - Basic	242.6		242.6		242.6
Average Common Shares Outstanding - Diluted	244.4		244.5		243.0
Union Electric Company
Operating Revenues:
Electric	3,388		3,379		3,132
Gas	164		161		139
Other	1		1		1
Total operating revenues	3,553		3,541		3,272
Operating Expenses:
Fuel	826		845		714
Purchased power	119		127		78
Gas purchased for resale	82		78		64
Other operations and maintenance	946		915		827
Depreciation and amortization	473		454		440
Taxes other than income taxes	322		319		304
Total operating expenses	2,768		2,738		2,427
Operating Income	785		803		845
Other Income and Expenses:
Miscellaneous income	60		58		63
Miscellaneous expense	12		11		14
Total other income (expense)	48		47		49
Interest charges	211		210		223
Income Before Income Taxes	622		640		671
Income taxes	229		242		252
Net Income (Loss)	393		398		419
Net Income (Loss):
Net income (loss) attributable to Ameren Corporation	393		398		419
Other Comprehensive Income	0		0		0
Comprehensive Income (Loss)	393		398		419
Preferred Stock Dividends	3		3		3
Net Income Available to Common Stockholder	390		395		416
Ameren Illinois Company
Operating Revenues:
Electric	1,522		1,461		1,739
Gas	976		847		786
Other			3
Total operating revenues	2,498		2,311		2,525
Operating Expenses:
Purchased power	343		380		705
Gas purchased for resale	533		448		408
Other operations and maintenance	771		693		684
Depreciation and amortization	263		243		221
Taxes other than income taxes	138		132		130
Total operating expenses	2,048		1,896		2,148
Operating Income	450		415		377
Other Income and Expenses:
Miscellaneous income	17		10		7
Miscellaneous expense	8		9		17
Total other income (expense)	9		1		(10)
Interest charges	112		143		129
Income Before Income Taxes	347		273		238
Income taxes	143		110		94
Net Income (Loss)	204		163		144
Net Income (Loss):
Net income (loss) attributable to Ameren Corporation	204		163		144
Pension and other postretirement activity, net of income taxes (benefit)	(3)		(3)		(3)
Comprehensive Income (Loss)	201		160		141
Preferred Stock Dividends	3		3		3
Net Income Available to Common Stockholder	$ 201		$ 160		$ 141

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