Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2011

Fair Value Measurements

Schedule of Fair Value Hierarchy of Assets and Liabilities Measured at Fair Value on Recurring Basis

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 June 30, 2011:

		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	$	-	$	-	$	72	$	72
	Natural gas		3		-		3		6
	Power		-		18		174		192
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		1		-		-		1
	Equity securities:
	U.S. large capitalization		234		-		-		234
	Debt securities:
	Corporate bonds		-		45		-		45
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		59		-		59
	Asset-backed securities		-		13		-		13
	Other		-		1		-		1
AMO	Derivative assets - commodity contracts(b):
	Heating oil		-		-		43		43
	Power		-		2		28		30
	Nuclear Decommissioning Trust Fund(c):
	Cash and cash equivalents		1		-		-		1
	Equity securities:
	U.S. large capitalization		234		-		-		234
	Debt securities:
	Corporate bonds		-		45		-		45
	Municipal bonds		-		2		-		2
	U.S. treasury and agency securities		-		59		-		59
	Asset-backed securities		-		13		-		13
	Other		-		1		-		1
AIC	Derivative assets - commodity contracts(b):
	Natural gas		-		-		2		2
	Power		-		-		69		69
Genco	Derivative assets - commodity contracts(b):
	Heating oil		-		-		22		22
	Natural gas		1		-		-		1
	Power		-		-		4		4
Liabilities:
Ameren(a)	Derivative liabilities - commodity contracts(b):
	Heating oil	$	-	$	-	$	4	$	4
	Natural gas		18		-		120		138
	Power		-		16		57		73
	Uranium		-		-		2		2
AMO	Derivative liabilities - commodity contracts(b):
	Heating oil		-		-		2		2
	Natural gas		9		-		11		20
	Power		-		1		3		4
	Uranium		-		-		2		2
AIC	Derivative liabilities - commodity contracts(b):
	Natural gas		5		-		108		113
	Power		-		-		273		273
Genco	Derivative liabilities - commodity contracts(b):
	Heating oil		-		-		1		1
	Natural gas		2		-		-		2
	Power		-		-		3		3

(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

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 June 30, 2011:

	Net derivative commodity contracts
Three Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other(c)
Heating oil:
Beginning balance at April 1, 2011	$	96		$	57		$	(a	)	$	29		$	10
Realized and unrealized gains (losses):
Included in earnings(b)		(5	)		-			(a	)		(3	)		(2	)
Included in regulatory assets/liabilities		(9	)		(9	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(14	)		(9	)		(a	)		(3	)		(2	)
Purchases		1			1			(a	)		-			-
Settlements		(15	)		(8	)		(a	)		(5	)		(2	)
Ending balance at June 30, 2011	$	68		$	41		$	(a	)	$	21		$	6
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	(14	)	$	(8	)	$	(a	)	$	(4	)	$	(2	)
Natural gas:
Beginning balance at April 1, 2011	$	(120	)	$	(12	)	$	(108	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(20	)		(1	)		(19	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(20	)		(1	)		(19	)		-			-
Purchases		1			-			1			-			-
Settlements		22			2			20			-			-
Ending balance at June 30, 2011	$	(117	)	$	(11	)	$	(106	)	$	-		$	-
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	(18	)	$	(1	)	$	(17	)	$	-		$	-
Power:
Beginning balance at April 1, 2011	$	31		$	2		$	(325	)	$	3		$	351
Realized and unrealized gains (losses):
Included in earnings(b)		(15	)		-			-			(1	)		(14	)
Included in OCI		5			-			-			-			5
Included in regulatory assets/liabilities		66			(1	)		77			(a	)		(10	)
Total realized and unrealized gains (losses)		56			(1	)		77			(1	)		(19	)
Purchases		50			29			-			-			21
Sales		(7	)		-			-			-			(7	)
Settlements		(16	)		(6	)		44			(1	)		(53	)
Transfers into Level 3		1			-			-			-			1
Transfers out of Level 3		2			1			-			-			1
Ending balance at June 30, 2011	$	117		$	25		$	(204	)	$	1		$	295
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	59		$	(1	)	$	68		$	(1	)	$	(7	)
Uranium:
Beginning balance at April 1, 2011	$	1		$	1		$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(3	)		(3	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(3	)		(3	)		(a	)		(a	)		(a	)
Ending balance at June 30, 2011	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)
Change in unrealized gains (losses) related to assets/liabilities held at June 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 three months ended June 30, 2010:

	Net derivative commodity contracts
Three Months	Ameren			Ameren Missouri			Ameren Illinois			Genco			Other(c)
Heating oil:
Beginning balance at April 1, 2010	$	54		$	31		$	(a	)	$	18		$	5
Realized and unrealized gains (losses):
Included in earnings(b)		(8	)		-			(a	)		(6	)		(2	)
Included in regulatory assets/liabilities		(9	)		(9	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(17	)		(9	)		(a	)		(6	)		(2	)
Purchases		33			17			(a	)		11			5
Settlements		(41	)		(23	)		(a	)		(13	)		(5	)
Ending balance at June 30, 2010	$	29		$	16		$	(a	)	$	10		$	3
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(16	)	$	(9	)	$	(a	)	$	(5	)	$	(2	)
Natural gas:
Beginning balance at April 1, 2010	$	(162	)	$	(18	)	$	(144	)	$	-		$	-
Realized and unrealized gains (losses):
Included in earnings(b)		-			-			-			-			-
Included in regulatory assets/liabilities		(6	)		(1	)		(5	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(6	)		(1	)		(5	)		-			-
Purchases		-			-			-			-			-
Settlements		30			4			26			-			-
Ending balance at June 30, 2010	$	(138	)	$	(15	)	$	(123	)	$	-		$	-
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(6	)	$	(1	)	$	(5	)	$	-		$	-
Power:
Beginning balance at April 1, 2010	$	37		$	5		$	(554	)	$	3		$	583
Realized and unrealized gains (losses):
Included in earnings(b)		6			-			-			-			6
Included in OCI		(18	)		-			-			-			(18	)
Included in regulatory assets/liabilities		29			1			98			(a	)		(70	)
Total realized and unrealized gains (losses)		17			1			98			-			(82	)
Purchases		25			5			17			(2	)		5
Sales		2			-			-			3			(1	)
Settlements		(19	)		(6	)		33			(1	)		(45	)
Transfers into Level 3		(1	)		-			-			-			(1	)
Transfers out of Level 3		(7	)		-			-			-			(7	)
Ending balance at June 30, 2010	$	54		$	5		$	(406	)	$	3		$	452
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(5	)	$	(3	)	$	67		$	-		$	(69	)
Uranium:
Beginning balance at April 1, 2010	$	(3	)	$	(3	)	$	(a	)	$	(a	)	$	(a	)
Realized and unrealized gains (losses):
Included in regulatory assets/liabilities		(1	)		(1	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(1	)		(1	)		(a	)		(a	)		(a	)
Ending balance at June 30, 2010	$	(4	)	$	(4	)	$	(a	)	$	(a	)	$	(a	)
Change in unrealized gains (losses) related to assets/liabilities held at June 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.

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 six months ended June 30, 2011:

	Net derivative commodity contracts
Six 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)		17			-			(a	)		12			5
Included in regulatory assets/liabilities		22			22			(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		39			22			(a	)		12			5
Purchases		2			2			(a	)		-			-
Settlements		(24	)		(13	)		(a	)		(8	)		(3	)
Ending balance at June 30, 2011	$	68		$	41		$	(a	)	$	21		$	6
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	30		$	18		$	(a	)	$	9		$	3
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		(13	)		(1	)		(12	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(13	)		(1	)		(12	)		-			-
Purchases		1			-			1			-			-
Settlements		43			4			39			-			-
Ending balance at June 30, 2011	$	(117	)	$	(11	)	$	(106	)	$	-		$	-
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	9		$	1		$	8		$	-		$	-
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		5			-			-			-			5
Included in regulatory assets/liabilities		64			6			47			(a	)		11
Total realized and unrealized gains (losses)		51			6			47			(1	)		(1	)
Purchases		59			29			-			-			30
Sales		(16	)		-			-			-			(16	)
Settlements		(16	)		(12	)		101			(1	)		(104	)
Transfers into Level 3		1			(1	)		-			-			2
Transfers out of Level 3		2			1			-			-			1
Ending balance at June 30, 2011	$	117		$	25		$	(204	)	$	1		$	295
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2011	$	59		$	-		$	64		$	(1	)	$	(4	)
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	)
Ending balance at June 30, 2011	$	(2	)	$	(2	)	$	(a	)	$	(a	)	$	(a	)
Change in unrealized gains (losses) related to assets/liabilities held at June 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 six months ended June 30, 2010:

	Net derivative commodity contracts
Six 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)		(10	)		-			(a	)		(8	)		(2	)
Included in regulatory assets/liabilities		(11	)		(11	)		(a	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(21	)		(11	)		(a	)		(8	)		(2	)
Purchases		32			18			(a	)		11			3
Settlements		(42	)		(23	)		(a	)		(14	)		(5	)
Ending balance at June 30, 2010	$	29		$	16		$	(a	)	$	10		$	3
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(18	)	$	(10	)	$	(a	)	$	(6	)	$	(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		(109	)		(14	)		(95	)		(a	)		(a	)
Total realized and unrealized gains (losses)		(109	)		(14	)		(95	)		-			-
Purchases		(4	)		-			(4	)		-			-
Settlements		42			5			37			-			-
Ending balance at June 30, 2010	$	(138	)	$	(15	)	$	(123	)	$	-		$	-
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(81	)	$	(10	)	$	(71	)	$	-		$	-
Power:
Beginning balance at January 1, 2010	$	38		$	(1	)	$	(422	)	$	1		$	460
Realized and unrealized gains (losses):
Included in earnings(b)		24			-			-			2			22
Included in OCI		6			-			-			-			6
Included in regulatory assets/liabilities		7			13			(69	)		(a	)		63
Total realized and unrealized gains (losses)		37			13			(69	)		2			91
Purchases		38			4			17			(4	)		21
Sales		(5	)		1			-			5			(11	)
Settlements		(29	)		(9	)		68			(1	)		(87	)
Transfers into Level 3		(1	)		-			-			-			(1	)
Transfers out of Level 3		(24	)		(3	)		-			-			(21	)
Ending balance at June 30, 2010	$	54		$	5		$	(406	)	$	3		$	452
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2010	$	(7	)	$	1		$	(79	)	$	1		$	70
Uranium:
Beginning balance at January 1, 2010	$	(2	)	$	(2	)	$	(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 June 30, 2010	$	(4	)	$	(4	)	$	(a	)	$	(a	)	$	(a	)
Change in unrealized gains (losses) related to assets/liabilities held at June 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.

Schedule of Carrying Amounts and Estimated Fair Values of Long-Term Debt and Capital Lease Obligations and Preferred Stock

	June 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)	$	6,859	$	7,666	$	7,008	$	7,661
Preferred stock		142		102		142		102
Ameren Missouri:
Long-term debt and capital lease obligations (including current portion)	$	3,954	$	4,378	$	3,954	$	4,281
Preferred stock		80		61		80		62
Ameren Illinois:
Long-term debt (including current portion)	$	1,658	$	1,956	$	1,807	$	2,067
Preferred stock		62		41		62		40
Genco:
Long-term debt (including current portion)	$	824	$	843	$	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.