Segment Information

3 Months Ended

Mar. 31, 2014

Segment Reporting [Abstract]

SEGMENT INFORMATION

SEGMENT INFORMATION

Ameren has two reportable segments: Ameren Missouri and Ameren Illinois. The Ameren Missouri segment for both Ameren and Ameren Missouri includes all of the operations of Ameren Missouri’s business as described in Note 1 - Summary of Significant Accounting Policies. The Ameren Illinois segment for both Ameren and Ameren Illinois includes all of the operations of Ameren Illinois’ business as described in Note 1 - Summary of Significant Accounting Policies. The category called Other primarily includes Ameren parent company activities, Ameren Services, and ATXI. In 2013, the Other category also included certain corporate activities previously included in the Merchant Generation segment.

The following table presents information about the reported revenues and specified items reflected in Ameren’s net income attributable to Ameren Corporation from continuing operations for the three months ended March 31, 2014, and 2013, and total assets in continuing operations as of March 31, 2014, and December 31, 2013.

Three Months	Ameren Missouri		Ameren Illinois		Other			Intersegment Eliminations			Ameren
2014
External revenues	$	811	$	774	$	9		$	—		$	1,594
Intersegment revenues	6		—		1			(7		)	—
Net income (loss) attributable to Ameren Corporation from continuing operations	47		53		(3		)	—			97
2013
External revenues	$	789	$	684	$	2		$	—		$	1,475
Intersegment revenues	7		—		2			(9		)	—
Net income (loss) attributable to Ameren Corporation from continuing operations	40		31		(17		)	—			54
As of March 31, 2014:
Total assets	$	12,948	$	7,640	$	898		$	(335	)	$	21,151	(a)
As of December 31, 2013:
Total assets	$	12,904	$	7,454	$	752		$	(233	)	$	20,877	(a)

(a)    Excludes total assets from discontinued operations of $15 million and $165 million as of March 31, 2014, and December 31, 2013, respectively.