Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2014

Fair Value Disclosures [Abstract]

Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Valuation Techniques

The following table describes the valuation techniques and unobservable inputs for the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy as of March 31, 2014:

		Fair Value								Weighted Average
		Assets		Liabilities			Valuation Technique(s)	Unobservable Input	Range
Level 3 Derivative asset and liability - commodity contracts(a):
Ameren	Fuel oils	$	5	$	(4	)	Option model	Volatilities(%)(b)	13 - 34	16
							Discounted cash flow	Counterparty credit risk(%)(c)(d)	0.25 - 0.99	0.63
	Natural gas	1		(1		)	Option model	Volatilities(%)(b)	27 - 102	40
								Nodal basis($/mmbtu)(c)	(0.3) - (0.2)	(0.2)
							Discounted cash flow	Nodal basis($/mmbtu)(c)	(0.2) - (0.1)	(0.1)
								Counterparty credit risk(%)(c)(d)	0.27 - 5	1
								Ameren Missouri credit risk(%)(c)(d)	0.43	(e)
	Power(f)	14		(124		)	Discounted cash flow	Average forward peak and off-peak pricing - forwards/swaps($/MWh)(c)	27 - 57	33
								Estimated auction price for FTRs($/MW)(b)	(1,109) - 2,981	474
								Nodal basis($/MWh)(c)	(6) - (1)	(3)
								Counterparty credit risk(%)(c)(d)	0.35	(e)
								Ameren Missouri and Ameren Illinois credit risk(%)(c)(d)	0.43	(e)
							Fundamental energy production model	Estimated future gas prices($/mmbtu)(b)	4 - 6	5
								Escalation rate(%)(b)(g)	2 - 3	3
							Contract price allocation	Estimated renewable energy credit costs($/credit)(b)	5 - 7	6
	Uranium	—		(5		)	Discounted cash flow	Average forward uranium pricing($/pound)(b)	34 - 40	35
Ameren Missouri	Fuel oils	$	5	$	(4	)	Option model	Volatilities(%)(b)	13 - 34	16
							Discounted cash flow	Counterparty credit risk(%)(c)(d)	0.25 - 0.99	0.63
	Natural gas	1		(1		)	Option model	Volatilities(%)(b)	27 - 102	40
								Nodal basis($/mmbtu)(c)	(0.3) - (0.2)	(0.2)
							Discounted cash flow	Nodal basis($/mmbtu)(c)	(0.2) - (0.1)	(0.1)
								Counterparty credit risk(%)(c)(d)	0.27 - 5	1
								Ameren Missouri credit risk(%)(c)(d)	0.43	(e)
	Power(f)	14		(4		)	Discounted cash flow	Average forward peak and off-peak pricing - forwards/swaps($/MWh)(c)	30 - 57	45
								Estimated auction price for FTRs($/MW)(b)	(1,109) - 2,981	474
								Nodal basis($/MWh)(c)	(3) - (1)	(2)
								Counterparty credit risk(%)(c)(d)	0.35	(e)
								Ameren Missouri credit risk(%)(c)(d)	0.43	(e)
	Uranium	—		(5		)	Discounted cash flow	Average forward uranium pricing($/pound)(b)	34 - 40	35
Ameren Illinois	Power(f)	$	—	$	(120	)	Discounted cash flow	Average forward peak and off-peak pricing - forwards/swaps($/MWh)(b)	27 - 40	32
								Nodal basis($/MWh)(b)	(6) - (1)	(3)
								Ameren Illinois credit risk(%)(c)(d)	0.43	(e)
							Fundamental energy production model	Estimated future gas prices($/mmbtu)(b)	4 - 6	5
								Escalation rate(%)(b)(g)	2 - 3	3
							Contract price allocation	Estimated renewable energy credit costs($/credit)(b)	5 - 7	6

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

(b) Generally, significant increases (decreases) in this input in isolation would result in a significantly higher (lower) fair value measurement.

(c) Generally, significant increases (decreases) in this input in isolation would result in a significantly lower (higher) fair value measurement.

(d) Counterparty credit risk is applied only to counterparties with derivative asset balances. Ameren Missouri and Ameren Illinois credit risk is applied only to counterparties with derivative liability balances.

(e) Not applicable.

(f) Power valuations use visible third-party pricing evaluated by month for peak and off-peak demand through 2018. Valuations beyond 2018 use fundamentally modeled pricing by month for peak and off-peak demand.

(g) Escalation rate applies to power prices 2026 and beyond.

The following table describes the valuation techniques and unobservable inputs for the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy as of December 31, 2013:

		Fair Value								Weighted Average
		Assets		Liabilities			Valuation Technique(s)	Unobservable Input	Range
Level 3 Derivative asset and liability – commodity contracts(a):
Ameren	Fuel oils	$	8	$	(3	)	Option model	Volatilities(%)(b)	10 - 35	16
							Discounted cash flow	Counterparty credit risk(%)(c)(d)	0.26 - 2	1
	Power(e)	21		(110		)	Discounted cash flow	Average forward peak and off-peak pricing - forwards/swaps($/MWh)(c)	25 - 51	32
								Estimated auction price for FTRs($/MW)(b)	(1,594) - 945	305
								Nodal basis($/MWh)(c)	(3) - (1)	(2)
								Counterparty credit risk(%)(c)(d)	0.39 - 0.50	0.42
								Ameren Missouri and Ameren Illinois credit risk(%)(c)(d)	2	(f)
							Fundamental energy production model	Estimated future gas prices($/mmbtu)(b)	4 - 5	5
								Escalation rate(%)(b)(g)	3 - 4	4
							Contract price allocation	Estimated renewable energy credit costs($/credit)(b)	5 - 7	6
	Uranium	—		(6		)	Discounted cash flow	Average forward uranium pricing($/pound)(b)	34 - 41	36
Ameren Missouri	Fuel oils	$	8	$	(3	)	Option model	Volatilities(%)(b)	10 - 35	16
							Discounted cash flow	Counterparty credit risk(%)(c)(d)	0.26 - 2	1
	Power(e)	21		(2		)	Discounted cash flow	Average forward peak and off-peak pricing - forwards/swaps($/MWh)(c)	25 - 51	40
								Estimated auction price for FTRs($/MW)(b)	(1,594) - 945	305
								Nodal basis($/MWh)(c)	(3) - (1)	(2)
								Counterparty credit risk(%)(c)(d)	0.39 - 0.50	0.42
								Ameren Missouri credit risk(%)(c)(d)	2	(f)
	Uranium	—		(6		)	Discounted cash flow	Average forward uranium pricing($/pound)(b)	34 - 41	36
Ameren Illinois	Power(e)	$	—	$	(108	)	Discounted cash flow	Average forward peak and off-peak pricing - forwards/swaps($/MWh)(b)	27 - 36	30
								Nodal basis($/MWh)(b)	(4) - 0	(2)
								Ameren Illinois credit risk(%)(c)(d)	2	(f)
							Fundamental energy production model	Estimated future gas prices($/mmbtu)(b)	4 - 5	5
								Escalation rate(%)(b)(g)	3 - 4	4
							Contract price allocation	Estimated renewable energy credit costs($/credit)(b)	5 - 7	6

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

(b) Generally, significant increases (decreases) in this input in isolation would result in a significantly higher (lower) fair value measurement.

(c) Generally, significant increases (decreases) in this input in isolation would result in a significantly lower (higher) fair value measurement.

(d) Counterparty credit risk is applied only to counterparties with derivative asset balances. Ameren Missouri and Ameren Illinois credit risk is applied only to counterparties with derivative liability balances.

(e) Power valuations use visible third-party pricing evaluated by month for peak and off-peak demand through 2017. Valuations beyond 2017 use fundamentally modeled pricing by month for peak and off-peak demand.

(f)

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 March 31, 2014:

		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	Derivative assets - commodity contracts(a):
	Fuel oils	$	1	$	—	$	5	$	6
	Natural gas	—		6		1		7
	Power	—		1		14		15
	Total derivative assets - commodity contracts	$	1	$	7	$	20	$	28
	Nuclear decommissioning trust fund:
	Cash and cash equivalents	$	2	$	—	$	—	$	2
	Equity securities:
	U.S. large capitalization	327		—		—		327
	Debt securities:
	Corporate bonds	—		61		—		61
	Municipal bonds	—		2		—		2
	U.S. treasury and agency securities	—		94		—		94
	Asset-backed securities	—		14		—		14
	Other	—		1		—		1
	Total nuclear decommissioning trust fund	$	329	$	172	$	—	$	501	(b)
	Total Ameren	$	330	$	179	$	20	$	529
Ameren	Derivative assets - commodity contracts(a):
Missouri	Fuel oils	$	1	$	—	$	5	$	6
	Natural gas	—		1		1		2
	Power	—		1		14		15
	Total derivative assets - commodity contracts	$	1	$	2	$	20	$	23
	Nuclear decommissioning trust fund:
	Cash and cash equivalents	$	2	$	—	$	—	$	2
	Equity securities:
	U.S. large capitalization	327		—		—		327
	Debt securities:
	Corporate bonds	—		61		—		61
	Municipal bonds	—		2		—		2
	U.S. treasury and agency securities	—		94		—		94
	Asset-backed securities	—		14		—		14
	Other	—		1		—		1
	Total nuclear decommissioning trust fund	$	329	$	172	$	—	$	501	(b)
	Total Ameren Missouri	$	330	$	174	$	20	$	524
Ameren	Derivative assets - commodity contracts(a):
Illinois	Natural gas	$	—	$	5	$	—	$	5
Liabilities:
Ameren	Derivative liabilities - commodity contracts(a):
	Fuel oils	$	—	$	—	$	4	$	4
	Natural gas	2		34		1		37
	Power	—		2		124		126
	Uranium	—		—		5		5
	Total Ameren	$	2	$	36	$	134	$	172
Ameren	Derivative liabilities - commodity contracts(a):
Missouri	Fuel oils	$	—	$	—	$	4	$	4
	Natural gas	2		5		1		8
	Power	—		2		4		6
	Uranium	—		—		5		5
	Total Ameren Missouri	$	2	$	7	$	14	$	23
Ameren	Derivative liabilities - commodity contracts(a):
Illinois	Natural gas	$	—	$	29	$	—	$	29
	Power	—		—		120		120
	Total Ameren Illinois	$	—	$	29	$	120	$	149

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

(b) Balance excludes $2 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, 2013:

		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	Derivative assets - commodity contracts(a):
	Fuel oils	$	1	$	—	$	8	$	9
	Natural gas	—		2		—		2
	Power	—		2		21		23
	Total derivative assets - commodity contracts	$	1	$	4	$	29	$	34
	Nuclear decommissioning trust fund:
	Cash and cash equivalents	$	3	$	—	$	—	$	3
	Equity securities:
	U.S. large capitalization	332		—		—		332
	Debt securities:
	Corporate bonds	—		52		—		52
	Municipal bonds	—		2		—		2
	U.S. treasury and agency securities	—		94		—		94
	Asset-backed securities	—		10		—		10
	Other	—		1		—		1
	Total nuclear decommissioning trust fund	$	335	$	159	$	—	$	494
	Total Ameren	$	336	$	163	$	29	$	528
Ameren	Derivative assets - commodity contracts(a):
Missouri	Fuel oils	$	1	$	—	$	8	$	9
	Natural gas	—		1		—		1
	Power	—		2		21		23
	Total derivative assets - commodity contracts	$	1	$	3	$	29	$	33
	Nuclear decommissioning trust fund:
	Cash and cash equivalents	$	3	$	—	$	—	$	3
	Equity securities:
	U.S. large capitalization	332		—		—		332
	Debt securities:
	Corporate bonds	—		52		—		52
	Municipal bonds	—		2		—		2
	U.S. treasury and agency securities	—		94		—		94
	Asset-backed securities	—		10		—		10
	Other	—		1		—		1
	Total nuclear decommissioning trust fund	$	335	$	159	$	—	$	494
	Total Ameren Missouri	$	336	$	162	$	29	$	527
Ameren	Derivative assets - commodity contracts(a):
Illinois	Natural gas	$	—	$	1	$	—	$	1
Liabilities:
Ameren	Derivative liabilities - commodity contracts(a):
	Fuel oils	$	—	$	—	$	3	$	3
	Natural gas	3		54		—		57
	Power	—		2		110		112
	Uranium	—		—		6		6
	Total Ameren	$	3	$	56	$	119	$	178
Ameren	Derivative liabilities - commodity contracts(a):
Missouri	Fuel oils	$	—	$	—	$	3	$	3
	Natural gas	3		8		—		11
	Power	—		2		2		4
	Uranium	—		—		6		6
	Total Ameren Missouri	$	3	$	10	$	11	$	24
Ameren	Derivative liabilities - commodity contracts(a):
Illinois	Natural gas	$	—	$	46	$	—	$	46
	Power	—		—		108		108
	Total Ameren Illinois	$	—	$	46	$	108	$	154

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

Schedule Of Changes In The Fair Value Of Financial Assets And Liabilities Classified As Level Three 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 March 31, 2014:

		Net derivative commodity contracts
Three Months		Ameren Missouri			Ameren Illinois			Ameren
Fuel oils:
Beginning balance at January 1, 2014	$	5		$	(a)		$	5
Realized and unrealized gains (losses) included in regulatory assets/liabilities		(2	)		(a)			(2	)
Settlements		(2	)		(a)			(2	)
Ending balance at March 31, 2014	$	1		$	(a)		$	1
Change in unrealized gains (losses) related to assets/liabilities held at March 31, 2014	$	(1	)	$	(a)		$	(1	)
Natural gas:
Beginning balance at January 1, 2014	$	—		$	—		$	—
Purchases		—			(2	)		(2	)
Settlements		—			2			2
Ending balance at March 31, 2014	$	—		$	—		$	—
Change in unrealized gains (losses) related to assets/liabilities held at March 31, 2014	$	—		$	—		$	—
Power:
Beginning balance at January 1, 2014	$	19		$	(108	)	$	(89	)
Realized and unrealized gains (losses) included in regulatory assets/liabilities		(5	)		(12	)		(17	)
Settlements		(5	)		—			(5	)
Transfers out of Level 3		1			—			1
Ending balance at March 31, 2014	$	10		$	(120	)	$	(110	)
Change in unrealized gains (losses) related to assets/liabilities held at March 31, 2014	$	(1	)	$	(14	)	$	(15	)
Uranium:
Beginning balance at January 1, 2014	$	(6	)	$	(a)		$	(6	)
Settlements		1			(a)			1
Ending balance at March 31, 2014	$	(5	)	$	(a)		$	(5	)
Change in unrealized gains (losses) related to assets/liabilities held at March 31, 2014	$	—		$	(a)		$	—

(a) Not applicable.

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 March 31, 2013:

		Net derivative commodity contracts
Three Months		Ameren Missouri			Ameren Illinois			Ameren
Fuel oils:
Beginning balance at January 1, 2013	$	5		$	(a)		$	5
Purchases		1			(a)			1
Settlements		(1	)		(a)			(1	)
Ending balance at March 31, 2013	$	5		$	(a)		$	5
Change in unrealized gains (losses) related to assets/liabilities held at March 31, 2013	$	—		$	(a)		$	—
Natural gas:
Beginning balance at January 1, 2013	$	—		$	—		$	—
Realized and unrealized gains (losses) included in regulatory assets/liabilities		—			1			1
Purchases		—			1			1
Ending balance at March 31, 2013	$	—		$	2		$	2
Change in unrealized gains (losses) related to assets/liabilities held at March 31, 2013	$	—		$	—		$	—
Power:
Beginning balance at January 1, 2013	$	11		$	(111	)	$	(100	)
Realized and unrealized gains (losses) included in regulatory assets/liabilities		5			14			19
Settlements		(13	)		16			3
Transfers into Level 3		(2	)		—			(2	)
Transfers out of Level 3		1			—			1
Ending balance at March 31, 2013	$	2		$	(81	)	$	(79	)
Change in unrealized gains (losses) related to assets/liabilities held at March 31, 2013	$	(3	)	$	14		$	11
Uranium:
Beginning balance at January 1, 2013	$	(2	)	$	(a)		$	(2	)
Ending balance at March 31, 2013	$	(2	)	$	(a)		$	(2	)
Change in unrealized gains (losses) related to assets/liabilities held at March 31, 2013	$	—		$	(a)		$	—

(a) Not applicable.

Schedule Of Transfers Between Fair Value Hierarchy Levels

The following table summarizes all transfers between fair value hierarchy levels related to derivative commodity contracts for the three months ended March 31, 2014, and 2013:

	Three Months
	2014						2013
Derivative commodity contracts	Ameren Missouri		Ameren Illinois		Ameren		Ameren Missouri			Ameren Illinois		Ameren
Transfers into Level 3 / Transfers out of Level 2 - Power	$	—	$	—	$	—	$	(2	)	$	—	$	(2	)
Transfers out of Level 3 / Transfers into Level 2 - Power	1		—		1		1			—		1
Net fair value of Level 3 transfers	$	1	$	—	$	1	$	(1	)	$	—	$	(1	)

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

The following table presents the carrying amounts and estimated fair values of our long-term debt, capital lease obligations and preferred stock at March 31, 2014, and December 31, 2013:

	March 31, 2014				December 31, 2013
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Ameren:(a)
Long-term debt and capital lease obligations (including current portion)	$	5,874	$	6,530	$	6,038	$	6,584
Preferred stock	142		119		142		118
Ameren Missouri:
Long-term debt and capital lease obligations (including current portion)	$	3,758	$	4,200	$	3,757	$	4,124
Preferred stock	80		71		80		71
Ameren Illinois:
Long-term debt (including current portion)	$	1,692	$	1,903	$	1,856	$	2,028
Preferred stock	62		48		62		47

(a) Preferred stock is recorded in “Noncontrolling Interests” on the consolidated balance sheet.