Summary Of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2015

Schedule of Change in Asset Retirement Obligation

The following table provides a reconciliation of the beginning and ending carrying amount of AROs for the six months ended June 30, 2015:



	Ameren Missouri		Ameren Illinois^(a)		Ameren
Balance at December 31, 2014	$	389	$	7	$	396
Accretion in 2015^(b)	11		(c)		11
Change in estimates^(d)	182		(c)		182
Balance at June 30, 2015	$	582	$	7	$	589


(a)	Included in “Other deferred credits and liabilities” on the balance sheet.


(b)	Accretion expense was recorded as an increase to regulatory assets.


(c)	Less than $1 million.

(d)

The ARO increase resulted in a corresponding increase recorded to “Property and Plant, Net.” During the first quarter of 2015, Ameren and Ameren Missouri increased their AROs related to the decommissioning of the Callaway energy center by $99 million to reflect the 2015 cost study and funding analysis filed with the MoPSC, extension of the estimated operating life until 2044, and a reduction in the discount rate assumption. See Note 10 - Callaway Energy Center for additional information. In addition, during the second quarter of 2015, as a result of new federal regulations, Ameren and Ameren Missouri recorded an increase of $79 million to their AROs associated with CCR storage facilities. See Note 9 - Commitments and Contingencies for additional information. Also during the second quarter of 2015, Ameren and Ameren Missouri increased their AROs by $4 million due to a change in the estimated retirement dates of the Meramec and Rush Island energy centers as a result of the MoPSC’s April 2015 electric rate order.

Summary Of Nonvested Shares Related To Long-Term Incentive Plan

A summary of nonvested performance share units at June 30, 2015, and changes during the six months ended June 30, 2015, under the 2006 Incentive Plan and the 2014 Incentive Plan are presented below:



	Number of Performance Share Units		Weighted-average Fair Value Per Performance Share Unit
Nonvested at January 1, 2015	1,162,377		$	35.35
Granted^(a)	567,240		52.88
Forfeitures	(1,944	)	34.75
Vested^(b)	(85,694	)	46.79
Nonvested at June 30, 2015	1,641,979		$	40.81


(a)	Performance share units granted to certain executive and nonexecutive officers and other eligible employees in 2015 under the 2014 Incentive Plan.


(b)	Performance share units vested due to the attainment of retirement eligibility by certain employees. Actual shares issued for retirement-eligible employees will vary depending on actual performance over the three-year measurement period.

Schedule of Unrecognized Tax Benefits

The following table presents the total amount of reserves for unrecognized tax benefits (detriments) related to uncertain tax positions as of June 30, 2015, and December 31, 2014:



	June 30, 2015		December 31, 2014
Ameren	$	—	$	54
Ameren Missouri	—		—
Ameren Illinois	—		(1		)

Schedule of Unrecognized Tax Benefits That Would Impact Effective Tax Rate

The following table presents the amount of reserves for unrecognized tax benefits, included in the table above, related to uncertain tax positions that, if recognized, would have impacted results of operations as of December 31, 2014:



	December 31, 2014
Ameren	$	52
Ameren Missouri	—
Ameren Illinois	(1		)

Schedule of Excise Taxes

The following table presents excise taxes recorded in “Operating Revenues - Electric,” “Operating Revenues - Gas” and “Operating Expenses - Taxes other than income taxes” for the three and six months ended June 30, 2015 and 2014:



	Three Months				Six Months
	2015		2014		2015		2014
Ameren Missouri	$	41	$	39	$	75	$	73
Ameren Illinois	10		11		33		37
Ameren	$	51	$	50	$	108	$	110