Derivative Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2013

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Open Gross Derivative Volumes By Commodity Type

The following table presents open gross commodity contract volumes by commodity type as of March 31, 2013, and December 31, 2012:

	Quantity (in millions, except as indicated)
Commodity	Accrual & NPNS Contracts(a)		Other Derivatives(b)		Derivatives That Qualify for Regulatory Deferral(c)
	2013	2012	2013	2012	2013	2012
Coal (in tons)
Ameren Missouri & Ameren	91	96	(d)	(d)	(d)	(d)
Fuel oils (in gallons)(e)
Ameren Missouri & Ameren	(d)	(d)	(d)	(d)	67	26
Natural gas (in mmbtu)
Ameren Missouri	3	4	1	—	21	19
Ameren Illinois	12	16	(d)	(d)	137	128
Ameren	15	20	1	—	158	147
Power (in megawatthours)
Ameren Missouri	4	3	2	2	8	9
Ameren Illinois	19	21	(d)	(d)	12	14
Ameren	23	24	2	2	20	23
Renewable energy credits(f)
Ameren Missouri	3	3	(d)	(d)	(d)	(d)
Ameren Illinois	12	12	(d)	(d)	(d)	(d)
Ameren	15	15	(d)	(d)	(d)	(d)
Uranium (pounds in thousands)
Ameren Missouri & Ameren	4,950	5,142	(d)	(d)	480	446

(a) Accrual contracts include commodity contracts that do not qualify as derivatives. As of March 31, 2013, these contracts ran through December 2017, March 2015, September 2024, May 2032, and October 2024 for coal, natural gas, power, renewable energy credits, and uranium, respectively.

(b) As of March 31, 2013, these contracts ran through April 2013 and December 2014 for natural gas and power, respectively.

(c) As of March 31, 2013, these contracts ran through October 2015, March 2017, May 2032, and September 2014 for fuel oils, natural gas, power, and uranium, respectively.

(d) Not applicable.

(e) Fuel oils consist of heating oil, ultra-low sulfur diesel, and crude oil.

(f) A renewable energy credit is created for every one megawatthour of renewable energy generated. The Ameren Companies’ contracts include renewable energy credits from solar and wind-generated power.

Derivative Instruments Carrying Value

Authoritative accounting guidance permits companies to offset fair value amounts recognized for the right to reclaim cash collateral (a receivable) or the obligation to return cash collateral (a liability) against fair value amounts rec

Cumulative Pretax Net Gains (Losses) On All Derivative Instruments In OCI

The following table presents the cumulative amount of pretax net gains (losses) on all derivative instruments in regulatory assets or regulatory liabilities as of March 31, 2013, and December 31, 2012:

	Ameren			Ameren Missouri			Ameren Illinois
2013
Cumulative gains (losses) deferred in regulatory liabilities or assets:
Fuel oils derivative contracts(a)	$	4		$	4		$	—
Natural gas derivative contracts(b)	(71		)	(10		)	(61		)
Power derivative contracts(c)	(79		)	2			(81		)
Uranium derivative contracts(d)	(2		)	(2		)	—
2012
Cumulative gains (losses) deferred in regulatory liabilities or assets:
Fuel oils derivative contracts(a)	$	4		$	4		$	—
Natural gas derivative contracts(b)	(107		)	(14		)	(93		)
Power derivative contracts(c)	(99		)	12			(111		)
Uranium derivative contracts(d)	(2		)	(2		)	—

(a) Represents net gains on fuel oils derivative contracts at Ameren Missouri. These contracts are a partial hedge of Ameren Missouri’s transportation costs for coal through October 2015 as of March 31, 2013. Current gains deferred as regulatory liabilities include $4 million and $4 million at Ameren and Ameren Missouri as of March 31, 2013, respectively. Current losses deferred as regulatory assets include $1 million and $1 million at Ameren and Ameren Missouri as of March 31, 2013, respectively.

(b) Represents net losses associated with natural gas derivative contracts. These contracts are a partial hedge of natural gas requirements through March 2017 at Ameren and Ameren Missouri and through October 2016 at Ameren Illinois, in each case as of March 31, 2013. Current gains deferred as regulatory liabilities include $6 million, $1 million, and $5 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of March 31, 2013. Current losses deferred as regulatory assets include $45 million, $7 million, and $38 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of March 31, 2013.

(c) Represents net gains (losses) associated with power derivative contracts. These contracts are a partial hedge of power price requirements through May 2032 at Ameren and Ameren Illinois and through December 2015 at Ameren Missouri, in each case as of March 31, 2013. Current gains deferred as regulatory liabilities include $12 million and $12 million at Ameren and Ameren Missouri, respectively, as of March 31, 2013. Current losses deferred as regulatory assets include $21 million, $10 million, and $11 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of March 31, 2013.

(d) Represents net losses on uranium derivative contracts at Ameren Missouri. These contracts are a partial hedge of Ameren Missouri’s uranium requirements through September 2014 as of March 31, 2013. Current losses deferred as regulatory assets include $2 million and $2 million at Ameren and Ameren Missouri as of March 31, 2013, respectively.

Offsetting Derivative Assets and Liabilities

The following table provides the recognized gross derivative balances and the net amounts of those derivatives subject to an enforceable master netting arrangement or similar agreement as of March 31, 2013, and December 31, 2012:

			Gross Amounts Not Offset in the Balance Sheet
	Gross Amounts Recognized in the Balance Sheet		Derivative Instruments		Cash Collateral Received/Posted(a)		Net Amount
2013
Commodity contracts eligible to be offset:
Assets:
Ameren	$	37	$	20	$	—	$	17
Ameren Missouri	28		15		—		13
Ameren Illinois	9		5		—		4
Liabilities:
Ameren	$	183	$	20	$	39	$	124
Ameren Missouri	32		15		8		9
Ameren Illinois	151		5		31		115
2012
Commodity contracts eligible to be offset:
Assets:
Ameren	$	29	$	10	$	—	$	19
Ameren Missouri	28		9		—		19
Ameren Illinois	1		1		$	—	—
Liabilities:
Ameren	$	230	$	10	$	65	$	155
Ameren Missouri	25		9		7		9
Ameren Illinois	205		1		58		146

(a) Cash collateral received reduces gross asset balances and cash collateral posted reduces gross liability balances.

Maximum Exposure If Counterparties Fail To Perform On Contracts

The maximum exposure is based on the gross fair value of financial instruments, including accrual and NPNS contracts, which excludes collateral held, and does not consider the legally binding right to net transactions based on master trading and netting agreements.

	Affiliates		Commodity Marketing Companies		Electric Utilities		Financial Companies		Municipalities/ Cooperatives		Oil and Gas Companies		Total
2013
Ameren Missouri	$	1	$	1	$	1	$	10	$	3	$	—	$	16
Ameren Illinois	—		2		—		4		—		2		8
Ameren	$	1	$	3	$	1	$	14	$	3	$	2	$	24
2012
Ameren Missouri	$	—	$	2	$	3	$	14	$	3	$	—	$	22
Ameren Illinois	—		—		—		1		—		—		1
Ameren	$	—	$	2	$	3	$	15	$	3	$	—	$	23

Potential Loss On Counterparty Exposures

The following table presents the potential loss after consideration of collateral and application of master trading and netting agreements as of March 31, 2013, and December 31, 2012:

	Affiliates		Commodity Marketing Companies		Electric Utilities		Financial Companies		Municipalities/ Cooperatives		Oil and Gas Companies		Total
2013
Ameren Missouri	$	1	$	1	$	1	$	6	$	3	$	—	$	12
Ameren Illinois	—		2		—		2		—		—		4
Ameren	$	1	$	3	$	1	$	8	$	3	$	—	$	16
2012
Ameren Missouri	$	—	$	1	$	1	$	10	$	3	$	—	$	15
Ameren Illinois	—		—		—		—		—		—		—
Ameren	$	—	$	1	$	1	$	10	$	3	$	—	$	15

Derivative Instruments With Credit Risk-Related Contingent Features

The additional collateral required is the net liability position allowed under the master trading and netting agreements, assuming (1) the credit risk-related contingent features underlying these agreements were triggered on March 31, 2013, or December 31, 2012, and (2) those counterparties with rights to do so requested collateral:

	Aggregate Fair Value of Derivative Liabilities(a)		Cash Collateral Posted		Potential Aggregate Amount of Additional  Collateral Required(b)
2013
Ameren Missouri	$	66	$	1	$	62
Ameren Illinois	121		31		78
Ameren	$	187	$	32	$	140
2012
Ameren Missouri	$	78	$	3	$	71
Ameren Illinois	148		58		84
Ameren	$	226	$	61	$	155

(a) Prior to consideration of master trading and netting agreements and including NPNS contract exposures.

(b) As collateral requirements with certain counterparties are based on master trading and netting agreements, the aggregate amount of additional collateral required to be posted is determined after consideration of the effects of such agreements.

Derivatives That Qualify For Regulatory Deferral

The following table represents the net change in market value for derivatives that qualify for regulatory deferral for the three months ended March 31, 2013, and 2012:

		Gain (Loss) Recognized in Regulatory  Liabilities or Regulatory Assets
		2013			2012
Ameren	Fuel oils	$	—		$	5
	Natural gas	36			(18		)
	Power(a)	20			(162		)
	Total	$	56		$	(175	)
Ameren Missouri	Fuel oils	$	—		$	5
	Natural gas	4			(2		)
	Power	(10		)	(1		)
	Total	$	(6	)	$	2
Ameren Illinois	Natural gas	$	32		$	(16	)
	Power	30			(144		)
	Total	$	62		$	(160	)

(a) Amounts include intercompany eliminations.