Schedule II - Valuation And Qualifying Accounts

12 Months Ended

Dec. 31, 2017

Valuation and Qualifying Accounts [Abstract]

Valuation And Qualifying Accounts

SCHEDULE II – VALUATION AND QUALIFYING ACCOUNTS FOR THE YEARS ENDED DECEMBER 31, 2017, 2016, AND 2015
(in millions)
Column A	Column B		Column C							Column D		Column E
Description	Balance at Beginning of Period		(1) Charged to Costs and Expenses				(2) Charged to Other Accounts(a)			Deductions(b)		Balance at End of Period
Ameren:
Deducted from assets – allowance for doubtful accounts:
2017	$	19	$	26			$	7		$	33	$	19
2016	19		32				3			35		19
2015	21		33				5			40		19
Deferred tax valuation allowance:
2017	$	11	$	(6	)	(c)	$	—		$	—	$	5
2016	6		7				(2		)	—		11
2015	10		4				(8		)	—		6
Ameren Missouri:
Deducted from assets – allowance for doubtful accounts:
2017	$	7	$	9			$	—		$	9	$	7
2016	7		10				—			10		7
2015	8		13				—			14		7
Deferred tax valuation allowance:
2017	$	—	$	—			$	—		$	—	$	—
2016	—		—				—			—		—
2015	1		—				(1		)	—		—
Ameren Illinois:
Deducted from assets – allowance for doubtful accounts:
2017	$	12	$	17			$	7		$	24	$	12
2016	12		22				3			25		12
2015	13		20				5			26		12
Deferred tax valuation allowance:
2017	$	—	$	—			$	—		$	—	$	—
2016	—		—				—			—		—
2015	1		—				(1		)	—		—

(a) Amounts associated with the allowance for doubtful accounts relate to the uncollectible account reserve associated with receivables purchased by Ameren Illinois from alternative retail electric suppliers, as required by the Illinois Public Utilities Act. The amounts relating to the deferred tax valuation allowance are for items that have expired and were removed from both the underlying accumulated deferred income tax account as well as the offsetting valuation account.

(b) Uncollectible accounts charged off, less recoveries.

(c) Includes an adjustment of $3 million to Ameren (parent)’s valuation allowance for certain deferred tax assets existing at December 31, 2017, for the reduction in the income tax rate.