Retirement Benefits (Tables)

12 Months Ended

Dec. 31, 2012

The following table presents the benefit liability recorded on the balance sheets of each of the Ameren Companies as of December 31, 2012:



Ameren^(a)	$	1,183
Ameren Missouri	464
Ameren Illinois	408


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

Funded Status Of Benefit Plans And Amounts Included In Regulatory Assets And OCI

The following table presents the funded status of our pension and postretirement benefit plans as of December 31, 2012, and 2011. It also provides the amounts included in regulatory assets and accumulated OCI at December 31, 2012, and 2011, that have not been recognized in net periodic benefit costs.



	2012						2011
	Pension Benefits^(a)			Postretirement Benefits^(a)			Pension Benefits^(a)			Postretirement Benefits^(a)
Accumulated benefit obligation at end of year	$	3,929		(b)			$	3,645		(b)
Change in benefit obligation:
Net benefit obligation at beginning of year	$	3,865		$	1,257		$	3,451		$	1,120
Service cost	83			24			75			22
Interest cost	170			52			180			58
Plan amendments^(c)(d)	(6		)	(75		)	(16		)	—
Participant contributions	—			16			—			18
Actuarial loss	246			5			348			96
Curtailments^(e)	2			(1		)	—			—
Benefits paid	(209		)	(73		)	(173		)	(66		)
Early retiree reinsurance program receipt	(b)			2			(b)			3
Federal subsidy on benefits paid	(b)			4			(b)			6
Net benefit obligation at end of year	4,151			1,211			3,865			1,257
Change in plan assets:
Fair value of plan assets at beginning of year	2,876			896			2,722			797
Actual return on plan assets	392			110			224			9
Employer contributions	134			45			103			129
Federal subsidy on benefits paid	(b)			4			(b)			6
Early retiree reinsurance program receipt	(b)			2			(b)			3
Participant contributions	—			16			—			18
Benefits paid	(209		)	(73		)	(173		)	(66		)
Fair value of plan assets at end of year	3,193			1,000			2,876			896
Funded status - deficiency	958			211			989			361
Accrued benefit cost at December 31	$	958		$	211		$	989		$	361
Amounts recognized in the balance sheet consist of:
Noncurrent asset	$	—		$	(14	)	$	—		$	—
Current liability	3			2			3			3
Noncurrent liability	955			223			986			358
Net liability recognized	$	958		$	211		$	989		$	361
Amounts recognized in regulatory assets consist of:
Net actuarial loss	$	699		$	103		$	734		$	177
Prior service cost (credit)	(6		)	(24		)	(7		)	(28		)
Transition obligation	—			—			—			2
Amounts (pretax) recognized in accumulated OCI consist of:
Net actuarial loss	89			51			79			43
Prior service cost (credit)	(17		)	(65		)	(15		)	(7		)
Total	$	765		$	65		$	791		$	187


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


(b)	Not applicable.


(c)	In 2012, EEI's pension plan was amended to adjust the calculation of the future benefit obligation for all of its active employees from a traditional, final pay formula to a cash balance formula. Additionally, in 2012, EEI's management and labor union postretirement medical benefit plans were amended to adjust for moving to a Medicare Advantage plan.


(d)	In 2011, Ameren’s pension plan was amended to adjust the calculation of the future benefit obligation of approximately 430 labor union-represented employees from a traditional, final pay formula to a cash balance formula.

Assumptions Used To Determine Benefit Obligations

The following table presents the assumptions used to determine our benefit obligations at December 31, 2012, and 2011:



	Pension Benefits				Postretirement Benefits
	2012		2011		2012		2011
Discount rate at measurement date	4.00	%	4.50	%	4.00	%	4.50	%
Increase in future compensation	3.50		3.50		3.50		3.50
Medical cost trend rate (initial)	—		—		5.00		5.50
Medical cost trend rate (ultimate)	—		—		5.00		5.00
Years to ultimate rate	0		0		0		1 year

Schedule Of Cash Contributions Made To Benefit Plans

The following table presents the cash contributions made to our defined benefit retirement plan and to our postretirement plans during 2012, 2011, and 2010:



	Pension Benefits						Postretirement Benefits
	2012		2011		2010		2012		2011		2010
AMO	$	52	$	43	$	36	$	9	$	9	$	11
AIC	46		28		23		35		118		20
Other	36		32		22		1		2		5
Ameren^(a)	134		103		81		45		129		36


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

Target Allocation Of The Plans' Asset Categories

The following table presents our target allocations for 2013 and our pension and postretirement plans’ asset categories as of December 31, 2012, and 2011.



Asset Category	Target Allocation 2013	Percentage of Plan Assets at December 31,
Asset Category	Target Allocation 2013	2012		2011
Pension Plan:
Cash and cash equivalents	0 - 5 %	2	%	2	%
Equity securities:
U.S. large capitalization	29 - 39	34		33	%
U.S. small and mid-capitalization	2 - 12	7		7	%
International and emerging markets	9 - 19	13		11	%
Total equity	50 - 60	54		51	%
Debt securities	35 - 45	39		42	%
Real estate	0 - 9	4		4	%
Private equity	0 - 4	1		1	%
Total		100	%	100	%
Postretirement Plans:
Cash and cash equivalents	0 - 10 %	4	%	4	%
Equity securities:
U.S. large capitalization	33 - 43	40	%	38	%
U.S. small and mid-capitalization	3 - 13	8	%	8	%
International	10 - 20	14	%	13	%
Total equity	55 - 65	62	%	59	%
Debt securities	30 - 40	34	%	37	%
Total		100	%	100	%

Changes In The Fair Value Of Plan Assets Classified As Level 3

The following table summarizes the changes in the fair value of the pension plan assets classified as Level 3 in the fair value hierarchy for each of the years ended December 31, 2012, and 2011:



	Beginning Balance at January 1,		Actual Return on Plan Assets Related to Assets Still Held at the Reporting Date			Actual Return on Plan Assets Related to Assets Sold During the Period		Purchases, Sales, and Settlements, net			Net Transfers into (out of) of Level 3		Ending Balance at December 31,
2012:
Real estate	$	108	$	7		$	—	$	3		$	—	$	118
Private equity	23		(7		)	8		(5		)	—		19
2011:
Real estate	$	98	$	10		$	—	$	—		$	—	$	108
Private equity	28		(10		)	11		(6		)	—		23

Components Of Net Periodic Benefit Cost

The following table presents the components of the net periodic benefit cost of our pension and postretirement benefit plans during 2012, 2011, and 2010:



	Pension Benefits Ameren^(a)			Postretirement Benefits Ameren^(a)
2012
Service cost	$	83		$	24
Interest cost	170			52
Expected return on plan assets	(213		)	(60		)
Amortization of:
Transition obligation	—			2
Prior service cost	(3		)	(8		)
Actuarial loss	77			9
Curtailment loss^(b)	2			—
Net periodic benefit cost	$	116		$	19
2011
Service cost	$	75		$	22
Interest cost	180			58
Expected return on plan assets	(216		)	(54		)
Amortization of:
Transition obligation	—			2
Prior service cost	(1		)	(8		)
Actuarial loss	42			5
Net periodic benefit cost	$	80		$	25
2010
Service cost	$	68		$	20
Interest cost	185			62
Expected return on plan assets	(212		)	(56		)
Amortization of:
Transition obligation	—			2
Prior service cost	6			(8		)
Actuarial loss	18			1
Net periodic benefit cost	$	65		$	21


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


(b)	Includes EEI's pension and management postretirement benefit plans' curtailment loss of $2 million recognized in 2012 as a result of its employee reduction program.

Summary Of Estimated Amortizable Amounts From Regulatory Assets and Accumulated OCI Into Net Periodic Benefit Cost

The estimated amounts that will be amortized from regulatory assets and accumulated OCI into net periodic benefit cost in 2013 are as follows:



	Pension Benefits			Postretirement Benefits
	Ameren^(a)			Ameren^(a)
Regulatory assets:
Prior service cost (credit)	$	(1	)	$	(4	)
Net actuarial loss	97			19
Accumulated OCI:
Prior service cost (credit)	(2		)	(9		)
Net actuarial loss	7			5
Total	$	101		$	11


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

Summary Of Benefit Plan Costs Incurred

The Ameren Companies are responsible for their share of the pension and postretirement benefit costs. The following table presents the pension costs and the postretirement benefit costs incurred for the years ended December 31, 2012, 2011, and 2010:



	Pension Costs						Postretirement Costs
	2012		2011		2010		2012		2011		2010
Ameren Missouri	$	63	$	51	$	42	$	10	$	11	$	11
Ameren Illinois	37		16		10		4		11		7
Other ^(b)	16		13		13		5		3		3
Ameren^(a)(b)	116		80		65		19		25		21


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


(b)	Includes EEI's pension and management postretirement benefit plans' curtailment loss of $2 million recognized in 2012 as a result of its employee reduction program.

Schedule Of Expected Payments From Qualified Trust And Company Funds

The expected pension and postretirement benefit payments from qualified trust and company funds and the federal subsidy for postretirement benefits related to prescription drug benefits, which reflect expected future service, as of December 31, 2012, are as follows:



	Pension Benefits				Postretirement Benefits
	Paid from Qualified Trust		Paid from Company Funds		Paid from Qualified Trust		Paid from Company Funds		Federal Subsidy
2013	$	235	$	3	$	60	$	2	$	3
2014	243		3		62		2		3
2015	247		3		65		2		3
2016	253		3		68		2		4
2017	255		3		71		2		4
2018 - 2022	1,317		13		398		11		19

Assumptions Used To Determine Net Periodic Benefit Cost

The following table presents the assumptions used to determine net periodic benefit cost for our pension and postretirement benefit plans for the years ended December 31, 2012, 2011, and 2010:



	Pension Benefits						Postretirement Benefits
	2012		2011		2010		2012		2011		2010
Discount rate at measurement date	4.50	%	5.25	%	5.75	%	4.50	%	5.25	%	5.75	%
Expected return on plan assets	7.75		8.00		8.00		7.50		7.75		8.00
Increase in future compensation	3.50		3.50		3.50		3.50		3.50		3.50
Medical cost trend rate (initial)	—		—		—		5.50		6.00		6.50
Medical cost trend rate (ultimate)	—		—		—		5.00		5.00		5.00
Years to ultimate rate	0		0		0		1 year		2 years		3 years

Schedule Of Potential Changes In Key Assumptions

The table below reflects the sensitivity of Ameren’s plans to potential changes in key assumptions:



	Pension Benefits					Postretirement Benefits
	Service Cost and Interest Cost			Projected Benefit Obligation		Service Cost and Interest Cost		Postretirement Benefit Obligation
0.25% decrease in discount rate	$	(2	)	$	124	$	—	$	36
0.25% increase in salary scale	2			13		—		—
1.00% increase in annual medical trend	—			—		1		40
1.00% decrease in annual medical trend	—			—		—		(38		)

Schedule Of Matching Contributions

The following table presents the portion of the matching contribution to the Ameren 401(k) plan attributable to each of the Ameren Companies for the years ended December 31, 2012, 2011, and 2010:



	2012		2011		2010
Ameren Missouri	$	16	$	16	$	16
Ameren Illinois	9		8		8
Other	4		4		3
Ameren^(a)	29		28		27


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

Pension Benefits [Member]

Target Allocation Of The Plans' Asset Categories

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 - Fair Value Measurements, the pension plan assets measured at fair value as of December 31, 2012:



	Quoted Prices in Active Markets for Identified Assets (Level 1)			Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Cash and cash equivalents	$	1		$	30	$	—	$	31
Equity securities:
U.S. large capitalization	83			1,028		—		1,111
U.S. small and mid-capitalization	235			12		—		247
International and emerging markets	134			306		—		440
Debt securities:
Corporate bonds	—			832		—		832
Municipal bonds	—			177		—		177
U.S. treasury and agency securities	—			250		—		250
Other	—			42		—		42
Real estate	—			—		118		118
Private equity	—			—		19		19
Derivative assets	—			—		—		—
Derivative liabilities	(1		)	—		—		(1		)
Total	$	452		$	2,677	$	137	$	3,266
Less: Medical benefit assets at December 31^(a)								(102		)
Plus: Net receivables at December 31^(b)								29
Fair value of pension plans assets at year end								$	3,193


(a)	Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code (401(h) accounts) to fund a portion of the postretirement obligation.


(b)	Receivables related to pending security sales, offset by payables related to pending security purchases.

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 - Fair Value Measurements, the pension plan assets measured at fair value as of December 31, 2011:



	Quoted Prices in Active Markets for Identified Assets (Level 1)			Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Cash and cash equivalents	$	—		$	31	$	—	$	31
Equity securities:
U.S. large capitalization	72			922		—		994
U.S. small and mid-capitalization	202			11		—		213
International and emerging markets	115			213		—		328
Debt securities:
Corporate bonds	—			794		—		794
Municipal bonds	—			176		—		176
U.S. treasury and agency securities	—			230		—		230
Other	—			47		—		47
Real estate	—			—		108		108
Private equity	—			—		23		23
Derivative assets	1			—		—		1
Derivative liabilities	(1		)	—		—		(1		)
Total	$	389		$	2,424	$	131	$	2,944
Less: Medical benefit assets at December 31^(a)								(91		)
Plus: Net receivables at December 31^(b)								23
Fair value of pension plans assets at year end								$	2,876


(a)	Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code (401(h) accounts) to fund a portion of the postretirement obligation.


(b)	Receivables related to pending security sales, offset by payables related to pending security purchases.

Postretirement Benefits [Member]

Target Allocation Of The Plans' Asset Categories

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 - Fair Value Measurements, the postretirement benefit plans assets measured at fair value as of December 31, 2012:



	Quoted Prices in Active Markets for Identified Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Cash and cash equivalents	$	83	$	1	$	—	$	84
Equity securities:
U.S. large capitalization	277		88		—		365
U.S. small and mid-capitalization	66		—		—		66
International	51		69		—		120
Debt securities:
Corporate bonds	—		94		—		94
Municipal bonds	—		97		—		97
U.S. treasury and agency securities	—		78		—		78
Asset-backed securities	—		18		—		18
Other	—		22		—		22
Total	$	477	$	467	$	—	$	944
Plus: Medical benefit assets at December 31^(a)							102
Less: Net payables at December 31^(b)							(46		)
Fair value of postretirement benefit plans assets at year end							$	1,000


(a)	Medical benefit (health and welfare) component for 401(h) accounts to fund a portion of the postretirement obligation. These 401(h) assets are included in the pension plan assets shown above.


(b)	Payables related to pending security purchases, offset by Medicare, interest receivables, and receivables related to pending security sales.



	Quoted Prices in Active Markets for Identified Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Cash and cash equivalents	$	1	$	66	$	—	$	67
Equity securities:
U.S. large capitalization	235		78		—		313
U.S. small and mid-capitalization	57		—		—		57
International	44		56		—		100
Debt securities:
Corporate bonds	—		75		—		75
Municipal bonds	—		86		—		86
U.S. treasury and agency securities	—		82		—		82
Asset-backed securities	—		23		—		23
Other	—		35		—		35
Total	$	337	$	501	$	—	$	838
Plus: Medical benefit assets at December 31^(a)							91
Less: Net payables at December 31^(b)							(33		)
Fair value of postretirement benefit plans assets at year end							$	896


(a)	Medical benefit (health and welfare) component for 401(h) accounts to fund a portion of the postretirement obligation. These 401(h) assets are included in the pension plan assets shown above.


(b)	Payables related to pending security purchases, offset by Medicare, interest receivables, and receivables related to pending security sales.