Consolidated Statement Of Income (Loss) - USD ($) shares in Millions, $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Revenues:
Electric		$ 5,180	$ 4,913	$ 4,832
Gas		918	1,140	1,006
Total operating revenues		6,098	6,053	5,838
Operating Expenses:
Fuel		878	826	845
Purchased power		514	461	508
Gas purchased for resale		415	615	526
Other operations and maintenance		1,694	1,684	1,611
Provision for Callaway construction and operating license		69		0
Depreciation and amortization		796	745	706
Taxes other than income taxes		473	468	458
Total operating expenses		4,839	4,799	4,654
Operating Income		1,259	1,254	1,184
Other Income and Expenses:
Miscellaneous income	[1]	74	79	69
Miscellaneous expense	[1]	30	22	26
Total other income (expense)		44	57	43
Interest charges		355	341	398
Income Before Income Taxes		948	970	829
Income taxes		363	377	311
Income from Continuing Operations		585	593	518
Income (Loss) from Discontinued Operations, Net of Tax (Note 16)		51	(1)	(223)
Net Income (Loss)		636	592	295
Pension and other postretirement activity, net of income taxes (benefit)		6	(12)	30
Comprehensive Income (Loss)		636	574	300
Less: Net Income (Loss) Attributable to Noncontrolling Interests:
Continuing Operations		6	6	6
Net Income (Loss):
Net income attributable to Ameren Corporation - continuing operations		579	587	512
Discontinued Operations		51	(1)	(223)
Net income (loss) attributable to Ameren Corporation		$ 630	$ 586	$ 289
Earnings (Loss) per Common Share – Basic:
Continuing Operations - Basic		$ 2.39	$ 2.42	$ 2.11
Discontinued Operations - Basic		0.21	0.00	(0.92)
Earnings (Loss) per Common Share – Basic		2.60	2.42	1.19
Earnings (Loss) per Common Share – Diluted:
Continuing Operations - Diluted		2.38	2.40	2.10
Discontinued Operations - Diluted		0.21	0.00	(0.92)
Earnings (Loss) per Common Share – Diluted		2.59	2.40	1.18
Dividends per Common Share		$ 1.655	$ 1.61	$ 1.6
Average Common Shares Outstanding - Basic		242.6	242.6	242.6
Average Common Shares Outstanding - Diluted		243.6	244.4	244.5
Union Electric Company
Operating Revenues:
Electric		$ 3,470	$ 3,388	$ 3,379
Gas		137	164	161
Other		2	1	1
Total operating revenues		3,609	3,553	3,541
Operating Expenses:
Fuel		878	826	845
Purchased power		111	126	133
Gas purchased for resale		57	82	78
Other operations and maintenance		925	939	909
Provision for Callaway construction and operating license		69	0	0
Depreciation and amortization		492	473	454
Taxes other than income taxes		335	322	319
Total operating expenses		2,867	2,768	2,738
Operating Income		742	785	803
Other Income and Expenses:
Miscellaneous income		52	60	58
Miscellaneous expense		11	12	11
Total other income (expense)		41	48	47
Interest charges		219	211	210
Income Before Income Taxes		564	622	640
Income taxes		209	229	242
Net Income (Loss)		355	393	398
Other Comprehensive Income		0	0	0
Comprehensive Income (Loss)		355	393	398
Net Income (Loss):
Net income (loss) attributable to Ameren Corporation		355	393	398
Preferred Stock Dividends		3	3	3
Net Income Available to Common Stockholder		352	390	395
Ameren Illinois Company
Operating Revenues:
Electric		1,683	1,522	1,461
Gas		783	976	847
Other				3
Total operating revenues		2,466	2,498	2,311
Operating Expenses:
Purchased power		420	343	380
Gas purchased for resale		358	533	448
Other operations and maintenance		797	771	693
Depreciation and amortization		295	263	243
Taxes other than income taxes		130	138	132
Total operating expenses		2,000	2,048	1,896
Operating Income		466	450	415
Other Income and Expenses:
Miscellaneous income		21	17	10
Miscellaneous expense		12	8	9
Total other income (expense)		9	9	1
Interest charges		131	112	143
Income Before Income Taxes		344	347	273
Income taxes		127	143	110
Net Income (Loss)		217	204	163
Pension and other postretirement activity, net of income taxes (benefit)		(3)	(3)	(3)
Comprehensive Income (Loss)		214	201	160
Net Income (Loss):
Net income (loss) attributable to Ameren Corporation		217	204	163
Preferred Stock Dividends		3	3	3
Net Income Available to Common Stockholder		$ 214	$ 201	$ 160

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