Derivative Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2013

Derivative Instrument Detail [Abstract]

Open Gross Derivative Volumes By Commodity Type

The following table presents open gross commodity contract volumes by commodity type for derivative assets and liabilities as of December 31, 2013, and 2012. As of December 31, 2013, these contracts ran through October 2016, October 2019, May 2032, and October 2016 for fuel oils, natural gas, power, and uranium, respectively.

	Quantity (in millions, except as indicated)
	2013			2012
Commodity	Ameren Missouri	Ameren Illinois	Ameren	Ameren Missouri	Ameren Illinois	Ameren
Fuel oils (in gallons)(a)	66	(b)	66	70	(b)	70
Natural gas (in mmbtu)	28	108	136	19	128	147
Power (in megawatthours)	3	11	14	11	14	25
Uranium (pounds in thousands)	796	(b)	796	446	(b)	446

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

(b) Not applicable.

Derivative Instruments Carrying Value

The following table presents the carrying value and balance sheet location of all derivative instruments as of December 31, 2013, and 2012:

	Balance Sheet Location		Ameren Missouri		Ameren Illinois		Ameren
2013
Derivative assets not designated as hedging instruments(a)
Commodity contracts:
Fuel oils	Other current assets	$	6	$	—	$	6
	Other assets		3		—		3
Natural gas	Other current assets		1		1		2
Power	Other current assets		23		—		23
	Total assets	$	33	$	1	$	34
Derivative liabilities not designated as hedging instruments(a)
Commodity contracts:
Fuel oils	MTM derivative liabilities	$	(b)	$	—	$	2
	Other current liabilities		2		—		—
	Other deferred credits and liabilities		1		—		1
Natural gas	MTM derivative liabilities		(b)		27		32
	Other current liabilities		5		—		—
	Other deferred credits and liabilities		6		19		25
Power	MTM derivative liabilities		(b)		9		13
	Other current liabilities		4		—		—
	Other deferred credits and liabilities		—		99		99
Uranium	MTM derivative liabilities		(b)		—		5
	Other current liabilities		5		—		—
	Other deferred credits and liabilities		1		—		1
	Total liabilities	$	24	$	154	$	178
2012
Derivative assets not designated as hedging instruments(a)
Commodity contracts:
Fuel oils	Other current assets	$	8	$	—	$	8
	Other assets		4		—		4
Natural gas	Other current assets		—		1		1
	Other assets		1		—		1
Power	Other current assets		14		—		14
	Other assets		1		—		1
	Total assets	$	28	$	1	$	29
Derivative liabilities not designated as hedging instruments(a)
Commodity contracts:
Fuel oils	MTM derivative liabilities	$	(b)	$	—	$	2
	Other current liabilities		2		—		—
	Other deferred credits and liabilities		2		—		2
Natural gas	MTM derivative liabilities		(b)		56		64
	Other current liabilities		8		—		—
	Other deferred credits and liabilities		7		38		45
Power	MTM derivative liabilities		(b)		21		25
	Other current liabilities		4		—		—
	Other deferred credits and liabilities		—		90		90
Uranium	MTM derivative liabilities		(b)		—		1
	Other current liabilities		1		—		—
	Other deferred credits and liabilities		1		—		1
	Total liabilities	$	25	$	205	$	230

(a) Includes derivatives subject to regulatory deferral.

(b) Balance sheet line item not applicable to registrant.

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 deferred in regulatory assets or regulatory liabilities as of December 31, 2013, and 2012:

		Ameren Missouri			Ameren Illinois			Ameren
2013
Cumulative gains (losses) deferred in regulatory liabilities or assets:
Fuel oils derivative contracts(a)	$	2		$	—		$	2
Natural gas derivative contracts(b)		(10	)		(45	)		(55	)
Power derivative contracts(c)		19			(108	)		(89	)
Uranium derivative contracts(d)		(6	)		—			(6	)
2012
Cumulative gains (losses) deferred in regulatory liabilities or assets:
Fuel oils derivative contracts(a)	$	4		$	—		$	4
Natural gas derivative contracts(b)		(14	)		(93	)		(107	)
Power derivative contracts(c)		12			(111	)		(99	)
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 2016, as of December 31, 2013. Current gains deferred as regulatory liabilities include $3 million and $3 million at Ameren and Ameren Missouri as of December 31, 2013, respectively. Current losses deferred as regulatory assets include $1 million and $1 million at Ameren and Ameren Missouri as of December 31, 2013, respectively.

(b) Represents net losses associated with natural gas derivative contracts. These contracts are a partial hedge of natural gas requirements through October 2019 at Ameren and Ameren Missouri and through March 2017 at Ameren Illinois, in each case as of December 31, 2013. Current gains deferred as regulatory liabilities include $2 million, $1 million, and $1 million at Ameren, Ameren Missouri, and Ameren Illinois, respectively, as of December 31, 2013. Current losses deferred as regulatory assets include $32 million, $5 million, and $27 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of December 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 December 31, 2013. Current gains deferred as regulatory liabilities include $23 million and $23 million at Ameren and Ameren Missouri, respectively, as of December 31, 2013. Current losses deferred as regulatory assets include $13 million, $4 million, and $9 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of December 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 October 2016, as of December 31, 2013. Current losses deferred as regulatory assets include $5 million and $5 million at Ameren and Ameren Missouri as of December 31, 2013, respectively.

Derivative Instruments With Credit Risk-Related Contingent Features

The following table presents, as of December 31, 2013, and 2012, the aggregate fair value of all derivative instruments with credit risk-related contingent features in a gross liability position, the cash collateral posted, and the aggregate amount of additional collateral that could be required to be posted with counterparties. 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 December 31, 2013, or 2012, respectively, 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	$	70	$	2	$	67
Ameren Illinois	75		15		55
Ameren	$	145	$	17	$	122
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 and accrual 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 associated with derivatives that qualify for regulatory deferral for the years ended December 31, 2013 and 2012:

		Gain (Loss) Recognized in Regulatory Liabilities or Regulatory Assets
		2013			2012
Ameren (a)	Fuel oils	$	(2	)	$	(15	)
	Natural gas	52			84
	Power	10			(180		)
	Uranium	(4		)	(1		)
	Total	$	56		$	(112	)
Ameren Missouri	Fuel oils	$	(2	)	$	(15	)
	Natural gas	4			10
	Power	7			(9		)
	Uranium	(4		)	(1		)
	Total	$	5		$	(15	)
Ameren Illinois	Natural gas	$	48		$	74
	Power	3			29
	Total	$	51		$	103

(a) Amounts include intercompany eliminations.

Offsetting Derivative Assets and Liabilities [Table Text Block]

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 December 31, 2013, and 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 Missouri	$	33	$	9	$	—	$	24
Ameren Illinois		1		1		—		—
Ameren	$	34	$	10	$	—	$	24
Liabilities:
Ameren Missouri	$	24	$	9	$	9	$	6
Ameren Illinois		154		1		15		138
Ameren	$	178	$	10	$	24	$	144
2012
Commodity contracts eligible to be offset:
Assets:
Ameren Missouri	$	28	$	9	$	—	$	19
Ameren Illinois		1		1		—		—
Ameren	$	29	$	10	$	—	$	19
Liabilities:
Ameren Missouri	$	25	$	9	$	7	$	9
Ameren Illinois		205		1		58		146
Ameren	$	230	$	10	$	65	$	155

(a) Cash collateral received reduces gross asset balances and is included in “Other current liabilities” and “Other deferred credits and liabilities” on the balance sheet. Cash collateral posted reduces gross liability balances and is included in “Other current assets” and “Other assets” on the balance sheet.