Segment Information (Tables)

9 Months Ended

Sep. 30, 2013

Segment Reporting [Abstract]

Schedule Of Segment Reporting Information By Segment

The following table presents information about the revenues and specified items included in net income attributable to Ameren Corporation from continuing operations for the three and nine months ended September 30, 2013, and 2012, and total assets as of September 30, 2013, and December 31, 2012.

Three Months	Ameren Missouri		Ameren Illinois		Other			Intersegment Eliminations			Consolidated
2013
External revenues	$	1,088	$	547	$	3		$	—		$	1,638
Intersegment revenues	5		—		1			(6		)	—
Net income (loss) attributable to Ameren Corporation from continuing operations	238		77		(10		)	—			305
2012
External revenues	$	1,059	$	647	$	3		$	—		$	1,709
Intersegment revenues	5		1		—			(6		)	—
Net income (loss) attributable to Ameren Corporation from continuing operations	236		71		2			—			309
Nine Months
2013
External revenues	$	2,760	$	1,744	$	12		$	—		$	4,516
Intersegment revenues	18		3		2			(23		)	—
Net income (loss) attributable to Ameren Corporation from continuing operations	362		139		(37		)	—			464
2012
External revenues	$	2,583	$	1,935	$	5		$	—		$	4,523
Intersegment revenues	16		1		2			(19		)	—
Net income (loss) attributable to Ameren Corporation from continuing operations	400		130		(23		)	—			507
As of September 30, 2013:
Total assets	$	13,231	$	7,439	$	1,375		$	(1,055	)	$	20,990	(a)
As of December 31, 2012:
Total assets	$	13,043	$	7,282	$	1,228		$	(934	)	$	20,619	(a)

(a)    Excludes “Assets of discontinued operations.” See Note 2 - Divestiture Transactions and Discontinued Operations for additional information.