Consolidated Balance Sheet (USD $) In Millions, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Current Assets:
Cash and cash equivalents	$ 169		$ 184
Accounts receivable - trade (less allowance for doubtful accounts)	469		354
Unbilled revenue	226		291
Miscellaneous accounts and notes receivable	109		71
Materials and supplies	581		570
Current regulatory assets	173		247
Current accumulated deferred income taxes, net	43		170
Other current assets	108		98
Assets of discontinued operations (Note 2)	1,395		1,600
Total current assets	3,273		3,585
Property and Plant, Net	15,834		15,348
Investments and Other Assets:
Nuclear decommissioning trust fund	459		408
Goodwill	411		411
Intangible assets	19		14
Regulatory assets	1,729		1,786
Other assets	660		667
Total investments and other assets	3,278		3,286
TOTAL ASSETS	22,385		22,219
Current Liabilities:
Current maturities of long-term debt	884		355
Accounts and wages payable	414		533
Taxes accrued	159		50
Interest accrued	120		89
Customer deposits	106		107
Mark-to-market derivative liabilities	65		92
Current regulatory liabilities	149		100
Other current liabilities	190		168
Liabilities of discontinued operations (Note 2)	1,141		1,166
Total current liabilities	3,228		2,660
Long-term Debt, Net	5,274		5,802
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes, net	3,422		3,176
Accumulated deferred investment tax credits	65		70
Regulatory liabilities	1,703		1,589
Asset retirement obligations	392		375
Pension and other postretirement benefits	1,042		1,138
Other deferred credits and liabilities	534		642
Total deferred credits and other liabilities	7,158		6,990
Commitments and Contingencies
Stockholders' Equity:
Common Stock	2		2
Other paid-in capital	5,624		5,616
Retained earnings	967		1,006
Accumulated other comprehensive income (loss)	(19)		(8)
Stockholder's equity	6,574		6,616
Noncontrolling Interest	151	[1]	151	[1]
Total equity	6,725		6,767
TOTAL LIABILITIES AND EQUITY	22,385		22,219
Union Electric Company
Current Assets:
Cash and cash equivalents	100		148
Advances to money pool			24
Accounts receivable - trade (less allowance for doubtful accounts)	270		161
Accounts receivable - affiliates	9		4
Unbilled revenue	151		145
Miscellaneous accounts and notes receivable	76		48
Materials and supplies	370		397
Current regulatory assets	124		163
Other current assets	65		69
Total current assets	1,165		1,159
Property and Plant, Net	10,337		10,161
Investments and Other Assets:
Nuclear decommissioning trust fund	459		408
Intangible assets	19		14
Regulatory assets	808		852
Other assets	443		449
Total investments and other assets	1,729		1,723
TOTAL ASSETS	13,231		13,043
Current Liabilities:
Current maturities of long-term debt	309		205
Accounts and wages payable	186		345
Accounts payable - affiliates	61		66
Taxes accrued	288		28
Interest accrued	67		60
Current regulatory liabilities	61		18
Other current liabilities	97		77
Total current liabilities	1,069		799
Long-term Debt, Net	3,697		3,801
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes, net	2,472		2,443
Accumulated deferred investment tax credits	61		64
Regulatory liabilities	1,002		917
Asset retirement obligations	362		346
Pension and other postretirement benefits	423		461
Other deferred credits and liabilities	49		158
Total deferred credits and other liabilities	4,369		4,389
Commitments and Contingencies
Stockholders' Equity:
Common Stock	511		511
Other paid-in capital	1,556		1,556
Preferred stock not subject to mandatory redemption	80		80
Retained earnings	1,949		1,907
Stockholder's equity	4,096		4,054
TOTAL LIABILITIES AND EQUITY	13,231		13,043
Ameren Illinois Company
Current Assets:
Cash and cash equivalents	1
Accounts receivable - trade (less allowance for doubtful accounts)	185		182
Accounts receivable - affiliates	28		10
Unbilled revenue	75		146
Miscellaneous accounts and notes receivable	8		22
Materials and supplies	211		173
Current regulatory assets	49		84
Current accumulated deferred income taxes, net	35		85
Other current assets	33		47
Total current assets	625		749
Property and Plant, Net	5,369		5,052
Investments and Other Assets:
Tax receivable - Genco	37		39
Goodwill	411		411
Regulatory assets	916		934
Other assets	81		97
Total investments and other assets	1,445		1,481
TOTAL ASSETS	7,439		7,282
Current Liabilities:
Current maturities of long-term debt	150		150
Borrowings from money pool	21		24
Accounts and wages payable	189		146
Accounts payable - affiliates	86		86
Taxes accrued	17		18
Customer deposits	81		85
Mark-to-market derivative liabilities	48		77
Current environmental remediation	53		37
Current regulatory liabilities	88		82
Other current liabilities	114		92
Total current liabilities	847		797
Long-term Debt, Net	1,577		1,577
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes, net	1,095		1,025
Accumulated deferred investment tax credits	4		5
Regulatory liabilities	701		672
Pension and other postretirement benefits	376		406
Environmental remediation	194		216
Other deferred credits and liabilities	152		183
Total deferred credits and other liabilities	2,522		2,507
Commitments and Contingencies
Stockholders' Equity:
Common Stock	0		0
Other paid-in capital	1,965		1,965
Preferred stock not subject to mandatory redemption	62		62
Retained earnings	454		360
Accumulated other comprehensive income (loss)	12		14
Stockholder's equity	2,493		2,401
TOTAL LIABILITIES AND EQUITY	$ 7,439		$ 7,282

[1] Includes the 20% EEI ownership interest not owned by Ameren. The assets and liabilities of EEI were consolidated in Ameren’s balance sheet at a 100% ownership level and were included in “Current assets of discontinued operations” and “Current liabilities of discontinued operations.” The 20% ownership interest not owned by Ameren was included in “Noncontrolling interests” on Ameren’s September 30, 2013, and December 31, 2012 balance sheets. See Note 2 - Divestiture Transactions and Discontinued Operations for additional information.