Consolidated Statement of Income (Loss) - USD ($) shares in Millions, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Operating Revenues:
Electric		$ 1,250	$ 1,235	$ 2,393	$ 2,341
Gas		151	184	564	672
Total operating revenues		1,401	1,419	2,957	3,013
Operating Expenses:
Fuel		205	198	411	402
Purchased power		101	112	240	226
Gas purchased for resale		46	79	282	383
Other operations and maintenance		427	411	828	829
Provision for Callaway construction and operating license		69	0	69	0
Depreciation and amortization		200	183	393	364
Taxes other than income taxes		116	114	241	241
Total operating expenses		1,164	1,097	2,464	2,445
Operating Income		237	322	493	568
Other Income and Expenses:
Miscellaneous income	[1]	16	21	35	39
Miscellaneous expense	[1]	6	4	17	13
Total other income (expense)		10	17	18	26
Interest Charges		89	89	177	181
Income Before Income Taxes		158	250	334	413
Income Taxes		59	99	125	163
Income from Continuing Operations		99	151	209	250
Income (Loss) from Discontinued Operations, Net of Taxes (Note 12)		52	(1)	52	(2)
Net Income (Loss)		151	150	261	248
Pension and other postretirement benefit plan activity, net of income taxes (benefit)		4	3	4	3
Comprehensive Income		154	152	262	248
Less: Net Income (Loss) Attributable to Noncontrolling Interests:
Net Income from Continuing Operations Attributable to Noncontrolling Interests		1	1	3	3
Net Income (Loss):
Continuing Operations		98	150	206	247
Discontinued Operations		52	(1)	52	(2)
Net Income (Loss)		$ 150	$ 149	$ 258	$ 245
Earnings Per Share, Basic [Abstract]
Continuing Operations		$ 0.40	$ 0.62	$ 0.85	$ 1.02
Discontinued Operations		0.21	(0.01)	0.21	(0.01)
Earnings Per Share, Basic		0.61	0.61	1.06	1.01
Dividends per Common Share		$ 0.41	$ 0.40	$ 0.82	$ 0.80
Average Common Shares Outstanding - Basic		242.6	242.6	242.6	242.6
Union Electric Company
Operating Revenues:
Electric		$ 859	$ 871	$ 1,601	$ 1,620
Gas		24	28	82	96
Other Revenue, Net		1	1	1	1
Total operating revenues		884	900	1,684	1,717
Operating Expenses:
Fuel		205	198	411	402
Purchased power		19	29	58	64
Gas purchased for resale		7	11	38	51
Other operations and maintenance		229	221	440	446
Provision for Callaway construction and operating license		69	0	69	0
Depreciation and amortization		124	117	242	233
Taxes other than income taxes		85	81	165	159
Total operating expenses		738	657	1,423	1,355
Operating Income		146	243	261	362
Other Income and Expenses:
Miscellaneous income		12	16	23	30
Miscellaneous expense		2	2	5	6
Total other income (expense)		10	14	18	24
Interest Charges		55	54	110	106
Income Before Income Taxes		101	203	169	280
Income Taxes		39	76	65	105
Net Income (Loss)		62	127	104	175
Other Comprehensive Income		0	0	0	0
Comprehensive Income		62	127	104	175
Net Income (Loss):
Net Income (Loss)		62	127	104	175
Earnings Per Share, Basic [Abstract]
Preferred Stock Dividends		1	1	2	2
Net Income Available to Common Stockholder		61	126	102	173
Ameren Illinois Company
Operating Revenues:
Electric		386	364	776	717
Gas		127	155	482	576
Total operating revenues		513	519	1,258	1,293
Operating Expenses:
Purchased power		87	86	189	167
Gas purchased for resale		39	67	244	331
Other operations and maintenance		202	195	404	395
Depreciation and amortization		73	64	146	127
Taxes other than income taxes		29	32	72	78
Total operating expenses		430	444	1,055	1,098
Operating Income		83	75	203	195
Other Income and Expenses:
Miscellaneous income		4	5	11	8
Miscellaneous expense		2	1	7	5
Total other income (expense)		2	4	4	3
Interest Charges		33	29	66	59
Income Before Income Taxes		52	50	141	139
Income Taxes		20	21	55	56
Net Income (Loss)		32	29	86	83
Pension and other postretirement benefit plan activity, net of income taxes (benefit)		(1)	(1)	(2)	(2)
Comprehensive Income		31	28	84	81
Net Income (Loss):
Net Income (Loss)		32	29	86	83
Earnings Per Share, Basic [Abstract]
Preferred Stock Dividends		1	1	2	2
Net Income Available to Common Stockholder		$ 31	$ 28	$ 84	$ 81

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