Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2011

Schedule Of Fair Value Hierarchy Of Assets And Liabilities Measured At Fair Value On Recurring Basis


		Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Assets:
Ameren^(a)	Derivative assets - commodity contracts^(b):
	Heating oil	$	-	$	-	$	37	$	37
	Natural gas		4		-		2		6
	Power		-		7		160		167
	Nuclear Decommissioning Trust Fund^(c):
	Cash and cash equivalents		2		-		-		2
	Equity securities:
	U.S. large capitalization		200		-		-		200
	Debt securities:
	Corporate bonds		-		36		-		36
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		82		-		82
	Asset-backed securities		-		6		-		6
	Other		-		1		-		1
AMO	Derivative assets - commodity contracts^(b):
	Heating oil		-		-		23		23
	Power		-		2		23		25
	Nuclear Decommissioning Trust Fund^(c):
	Cash and cash equivalents		2		-		-		2
	Equity securities:
	U.S. large capitalization		200		-		-		200
	Debt securities:
	Corporate bonds		-		36		-		36
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		82		-		82
	Asset-backed securities		-		6		-		6
	Other		-		1		-		1
AIC	Derivative assets - commodity contracts^(b):
	Natural gas		-		-		2		2
	Power		-		-		88		88
Genco	Derivative assets - commodity contracts^(b):
	Heating oil		-		-		11		11
	Natural gas		1		-		-		1
	Power		-		-		-		-
Liabilities:
Ameren^(a)	Derivative liabilities - commodity contracts^(b):
	Heating oil	$	-	$	-	$	7	$	7
	Natural gas		20		-		130		150
	Power		-		5		46		51
	Uranium		-		-		1		1
AMO	Derivative liabilities - commodity contracts^(b):
	Heating oil		-		-		3		3
	Natural gas		9		-		11		20
	Power		-		1		5		6
	Uranium		-		-		1		1
AIC	Derivative liabilities - commodity contracts^(b):
	Natural gas		6		-		118		124
	Power		-		-		222		222
Genco	Derivative liabilities - commodity contracts^(b):
	Heating oil		-		-		3		3
	Natural gas		1		-		-		1
	Power		-		-		-		-

(a)	Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.

(b)	The derivative asset and liability balances are presented net of counterparty credit considerations.

(c)	Balance excludes $1 million of receivables, payables, and accrued income, net.

The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of December 31, 2010:


		Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Assets:
Ameren^(a)	Derivative assets - commodity contracts^(b):
	Heating oil	$	-	$	-	$	64	$	64
	Natural gas		3		-		2		5
	Power		-		17		86		103
	Uranium		-		-		2		2
	Nuclear Decommissioning Trust Fund^(c):
	Cash and cash equivalents		1		-		-		1
	Equity securities:
	U.S. large capitalization		228		-		-		228
	Debt securities:
	Corporate bonds		-		40		-		40
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		50		-		50
	Asset-backed securities		-		14		-		14
	Other		-		1		-		1
AMO	Derivative assets - commodity contracts^(b):
	Heating oil		-		-		37		37
	Natural gas		-		-		1		1
	Power		-		3		5		8
	Uranium		-		-		2		2
	Nuclear Decommissioning Trust Fund^(c):
	Cash and cash equivalents		1		-		-		1
	Equity securities:
	U.S. large capitalization		228		-		-		228
	Debt securities:
	Corporate bonds		-		40		-		40
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		50		-		50
	Asset-backed securities		-		14		-		14
	Other		-		1		-		1
AIC	Derivative assets - commodity contracts^(b):
	Natural gas		-		-		2		2
	Power		-		-		8		8
Genco	Derivative assets - commodity contracts^(b):
	Heating oil		-		-		21		21
	Natural gas		1		-		-		1
	Power		-		-		11		11
Liabilities:
Ameren^(a)	Derivative liabilities - commodity contracts^(b):
	Heating oil	$	-	$	-	$	13	$	13
	Natural gas		21		-		150		171
	Power		-		19		50		69
AMO	Derivative liabilities - commodity contracts^(b):
	Heating oil		-		-		7		7
	Natural gas		9		-		15		24
	Power		-		3		3		6
AIC	Derivative liabilities - commodity contracts^(b):
	Natural gas		7		-		136		143
	Power		-		-		360		360
Genco	Derivative liabilities - commodity contracts^(b):
	Heating oil		-		-		4		4
	Natural gas		2		-		-		2
	Power		-		-		8		8

(a)	Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.

(b)	The derivative asset and liability balances are presented net of counterparty credit considerations.

(c)	Balance excludes $1 million of receivables, payables, and accrued income, net.

Schedule Of Changes In The Fair Value Of Financial Assets And Liabilities Classified As Level 3 In The Fair Value Hierarchy


	Net derivative commodity contracts
Three Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other^(c)
Heating oil:
Beginning balance at July 1, 2011	$	68		$	41		$	(a	)	$	21		$	6
Realized and unrealized gains (losses):
Included in earnings^(b)		(7	)		-			(a	)		(5	)		(2	)
Included in regulatory assets/liabilities		(12	)		(12	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(19	)		(12	)		(a	)		(5	)		(2	)
Purchases		1			2			(a	)		(1	)		-
Sales		(1	)		(1	)		(a	)		-			-
Settlements		(19	)		(10	)		(a	)		(7	)		(2	)
Ending balance at September 30, 2011	$	30		$	20		$	(a	)	$	8		$	2

Change in unrealized gains (losses) related to assets/liabilities held at September 30, 2011	$	(22	)	$	(14	)	$	(a	)	$	(6	)	$	(2	)

Natural gas:
Beginning balance at July 1, 2011	$	(117	)	$	(11	)	$	(106	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings^(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(33	)		(2	)		(31	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(33	)		(2	)		(31	)		-			-
Purchases		(1	)		-			(1	)		-			-
Settlements		23			2			22			-			(1	)
Ending balance at September 30, 2011	$	(128	)	$	(11	)	$	(116	)	$	-		$	(1	)

Change in unrealized gains (losses) related to assets/liabilities held at September 30, 2011	$	(29	)	$	(2	)	$	(27	)	$	-		$	-

Power:
Beginning balance at July 1, 2011	$	117		$	25		$	(204	)	$	1		$	295
Realized and unrealized gains (losses):
Included in earnings^(b)		-			-			-			-			-
Included in OCI		(7	)		-			-			-			(7	)
Included in regulatory assets/liabilities		25			-			35			(a	)		(10	)
Total realized and unrealized gains (losses)		18			-			35			-			(17	)
Purchases		2			-			-			-			2
Sales		(1	)		-			-			-			(1	)
Settlements		(18	)		(7	)		35			(1	)		(45	)
Transfers into Level 3		(2	)		-			-			-			(2	)
Transfers out of Level 3		(2	)		-			-			-			(2	)
Ending balance at September 30, 2011	$	114		$	18		$	(134	)	$	-		$	230

Change in unrealized gains (losses) related to assets/liabilities held at September 30, 2011	$	22		$	-		$	26		$	-		$	(4	)

Uranium:
Beginning balance at July 1, 2011	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		-			-			(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		-			-			(a	)		(a	)		(a	)
Settlements		1			1			(a	)		(a	)		(a	)
Ending balance at September 30, 2011	$	(1	)	$	(1	)	$	(a	)	$	(a	)	$	(a	)

Change in unrealized gains (losses) related to assets/liabilities held at September 30, 2011	$	-		$	-		$	(a	)	$	(a	)	$	(a	)

(a)	Not applicable.

(b)	Net gains and losses on heating oil and natural gas derivative commodity contracts are recorded in Operating Expenses - Fuel, while net gains and losses on power derivative commodity contracts are recorded in Operating Revenues - Electric.

(c)	Includes amounts for Merchant Generation nonregistrant subsidiaries and intercompany eliminations.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the three months ended September 30, 2010:


	Net derivative commodity contracts
Three Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other^(c)
Heating oil:
Beginning balance at July 1, 2010	$	29		$	16		$	(a	)	$	10		$	3
Realized and unrealized gains (losses):
Included in earnings^(b)		4			-			(a	)		4			-
Included in regulatory assets/liabilities		8			8			(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		12			8			(a	)		4			-
Purchases		-			-			(a	)		-			-
Settlements		(3	)		(2	)		(a	)		(2	)		1
Ending balance at September 30, 2010	$	38		$	22		$	(a	)	$	12		$	4

Change in unrealized gains (losses) related to assets/liabilities held at September 30, 2010	$	13		$	8		$	(a	)	$	4		$	1

Natural gas:
Beginning balance at July 1, 2010	$	(138	)	$	(15	)	$	(123	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings^(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(70	)		(7	)		(63	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(70	)		(7	)		(63	)		-			-
Purchases		(1	)		-			(1	)		-			-
Settlements		27			4			23			-			-
Ending balance at September 30, 2010	$	(182	)	$	(18	)	$	(164	)	$	-		$	-

Change in unrealized gains (losses) related to assets/liabilities held at September 30, 2010	$	(65	)	$	(7	)	$	(58	)	$	-		$	-

Power:
Beginning balance at July 1, 2010	$	54		$	5		$	(406	)	$	3		$	452
Realized and unrealized gains (losses):
Included in earnings^(b)		20			-			-			-			20
Included in OCI		5			-			-			-			5
Included in regulatory assets/liabilities		(15	)		13			(92	)		(a	)		64
Total realized and unrealized gains (losses)		10			13			(92	)		-			89
Purchases		(2	)		-			2			(6	)		2
Sales		11			1			-			7			3
Settlements		(24	)		(8	)		32			(1	)		(47	)
Transfers into Level 3		-			-			-			-			-
Transfers out of Level 3		(1	)		-			-			-			(1	)
Ending balance at September 30, 2010	$	48		$	11		$	(464	)	$	3		$	498

Change in unrealized gains (losses) related to assets/liabilities held at September 30, 2010	$	(10	)	$	10		$	(96	)	$	(2	)	$	78

Uranium:
Beginning balance at July 1, 2010	$	(4	)	$	(4	)	$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		2			2			(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		2			2			(a	)		(a	)		(a	)
Ending balance at September 30, 2010	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)

Change in unrealized gains (losses) related to assets/liabilities held at September 30, 2010	$	1		$	1		$	(a	)	$	(a	)	$	(a	)

(a)	Not applicable.

(b)	Net gains and losses on heating oil and natural gas derivative commodity contracts are recorded in Operating Expenses - Fuel, while net gains and losses on power derivative commodity contracts are recorded in Operating Revenues - Electric.

(c)	Includes amounts for Merchant Generation nonregistrant subsidiaries and intercompany eliminations.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the nine months ended September 30, 2011:


	Net derivative commodity contracts
Nine Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other^(c)
Heating oil:
Beginning balance at January 1, 2011	$	51		$	30		$	(a	)	$	17		$	4
Realized and unrealized gains (losses):
Included in earnings^(b)		10			-			(a	)		7			3
Included in regulatory assets/liabilities		10			10			(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		20			10			(a	)		7			3
Purchases		3			4			(a	)		(1	)		-
Sales		(1	)		(1	)		(a	)		-			-
Settlements		(43	)		(23	)		(a	)		(15	)		(5	)
Ending balance at September 30, 2011	$	30		$	20		$	(a	)	$	8		$	2

Change in unrealized gains (losses) related to assets/liabilities held at September 30, 2011	$	4		$	2		$	(a	)	$	1		$	1

Natural gas:
Beginning balance at January 1, 2011	$	(148	)	$	(14	)	$	(134	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings^(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(46	)		(3	)		(43	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(46	)		(3	)		(43	)		-			-
Purchases		-			-			1			-			(1	)
Settlements		66			6			60			-			-
Ending balance at September 30, 2011	$	(128	)	$	(11	)	$	(116	)	$	-		$	(1	)

Change in unrealized gains (losses) related to assets/liabilities held at September 30, 2011	$	(34	)	$	(3	)	$	(31	)	$	-		$	-

Power:
Beginning balance at January 1, 2011	$	36		$	2		$	(352	)	$	3		$	383
Realized and unrealized gains (losses):
Included in earnings^(b)		(18	)		-			-			(1	)		(17	)
Included in OCI		(2	)		-			-			-			(2	)
Included in regulatory assets/liabilities		89			6			82			(a	)		1
Total realized and unrealized gains (losses)		69			6			82			(1	)		(18	)
Purchases		61			29			-			-			32
Sales		(17	)		-			-			-			(17	)
Settlements		(34	)		(19	)		136			(2	)		(149	)
Transfers into Level 3		(1	)		(1	)		-			-			-
Transfers out of Level 3		-			1			-			-			(1	)
Ending balance at September 30, 2011	$	114		$	18		$	(134	)	$	-		$	230

Change in unrealized gains (losses) related to assets/liabilities held at September 30, 2011	$	77		$	1		$	70		$	(1	)	$	7

Uranium:
Beginning balance at January 1, 2011	$	2		$	2		$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(4	)		(4	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(4	)		(4	)		(a	)		(a	)		(a	)
Settlements		1			1			(a	)		(a	)		(a	)
Ending balance at September 30, 2011	$	(1	)	$	(1	)	$	(a	)	$	(a	)	$	(a	)

Change in unrealized gains (losses) related to assets/liabilities held at September 30, 2011	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)

(a)	Not applicable.

(b)	Net gains and losses on heating oil and natural gas derivative commodity contracts are recorded in Operating Expenses - Fuel, while net gains and losses on power derivative commodity contracts are recorded in Operating Revenues - Electric.

(c)	Includes amounts for Merchant Generation nonregistrant subsidiaries and intercompany eliminations.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the nine months ended September 30, 2010:


	Net derivative commodity contracts
Nine Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other^(c)
Heating oil:
Beginning balance at January 1, 2010	$	60		$	32		$	(a	)	$	21		$	7
Realized and unrealized gains (losses):
Included in earnings^(b)		(6	)		-			(a	)		(4	)		(2	)
Included in regulatory assets/liabilities		(3	)		(3	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(9	)		(3	)		(a	)		(4	)		(2	)
Purchases		32			18			(a	)		11			3
Settlements		(45	)		(25	)		(a	)		(16	)		(4	)
Ending balance at September 30, 2010	$	38		$	22		$	(a	)	$	12		$	4

Change in unrealized gains (losses) related to assets/liabilities held at September 30, 2010	$	(5	)	$	(3	)	$	(a	)	$	(2	)	$	-

Natural gas:
Beginning balance at January 1, 2010	$	(67	)	$	(6	)	$	(61	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings^(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(179	)		(21	)		(158	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(179	)		(21	)		(158	)		-			-
Purchases		(5	)		-			(5	)		-			-
Settlements		69			9			60			-			-
Ending balance at September 30, 2010	$	(182	)	$	(18	)	$	(164	)	$	-		$	-

Change in unrealized gains (losses) related to assets/liabilities held at September 30, 2010	$	(116	)	$	(14	)	$	(102	)	$	-		$	-

Power:
Beginning balance at January 1, 2010	$	38		$	(1	)	$	(422	)	$	1		$	460
Realized and unrealized gains (losses):
Included in earnings^(b)		44			-			-			2			42
Included in OCI		11			-			-			-			11
Included in regulatory assets/liabilities		(8	)		26			(161	)		(a	)		127
Total realized and unrealized gains (losses)		47			26			(161	)		2			180
Purchases		36			4			19			(10	)		23
Sales		6			2			-			12			(8	)
Settlements		(53	)		(17	)		100			(2	)		(134	)
Transfers into Level 3		(1	)		-			-			-			(1	)
Transfers out of Level 3		(25	)		(3	)		-			-			(22	)
Ending balance at September 30, 2010	$	48		$	11		$	(464	)	$	3		$	498

Change in unrealized gains (losses) related to assets/liabilities held at September 30, 2010	$	6		$	2		$	(138	)	$	1		$	141

Uranium:
Beginning balance at January 1, 2010	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		-			-			(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		-			-			(a	)		(a	)		(a	)
Ending balance at September 30, 2010	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)

Change in unrealized gains (losses) related to assets/liabilities held at September 30, 2010	$	-		$	-		$	(a	)	$	(a	)	$	(a	)

(a)	Not applicable.

(b)	Net gains and losses on heating oil and natural gas derivative commodity contracts are recorded in Operating Expenses - Fuel, while net gains and losses on power derivative commodity contracts are recorded in Operating Revenues - Electric.

(c)	Includes amounts for Merchant Generation nonregistrant subsidiaries and intercompany eliminations.

Schedule Of Carrying Amounts And Estimated Fair Values Of Long-Term Debt And Capital Lease Obligations And Preferred Stock


	September 30, 2011				December 31, 2010
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Ameren:^(a)^(b)
Long-term debt and capital lease obligations (including current portion)	$	6,860	$	7,732	$	7,008	$	7,661
Preferred stock		142		89		142		102
Ameren Missouri:
Long-term debt and capital lease obligations (including current portion)	$	3,955	$	4,493	$	3,954	$	4,281
Preferred stock		80		53		80		62
Ameren Illinois:
Long-term debt (including current portion)	$	1,658	$	1,945	$	1,807	$	2,067
Preferred stock		62		36		62		40
Genco:
Long-term debt (including current portion)	$	824	$	817	$	824	$	826

(a)	Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.

(b)	Preferred stock not subject to mandatory redemption of the Ameren subsidiaries along with the 20% noncontrolling interest of EEI is recorded in Noncontrolling Interests on the balance sheet.

- Definition

Tabular disclosure of the fair value measurement of assets using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets) and gains or losses recognized in other comprehensive income, and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issuances, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs), by class of asset.

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