Selected Quarterly Information (Tables)

12 Months Ended

Dec. 31, 2015

Selected Quarterly Financial Information [Abstract]

Summary Of Selected Quarterly Information

SELECTED QUARTERLY INFORMATION (Unaudited) (In millions, except per share amounts)

Ameren	2015									2014
Quarter ended(a)	March 31		June 30		September 30		December 31			March 31			June 30			September 30			December 31
Operating revenues	$	1,556	$	1,401	$	1,833	$	1,308		$	1,594		$	1,419		$	1,670		$	1,370
Operating income	256		237		626		140			246			322			561			125
Net income	110		151		345		30			98			150			295			49
Net income attributable to Ameren common shareholders – continuing operations	$	108	$	98	$	343	$	30		$	97		$	150		$	294		$	46
Net income (loss) attributable to Ameren common shareholders – discontinued operations	—		52		—		(1		)	(1		)	(1		)	(1		)	2
Net income attributable to Ameren common shareholders	$	108	$	150	$	343	$	29		$	96		$	149		$	293		$	48
Earnings per common share – basic – continuing operations	$	0.45	$	0.40	$	1.42	$	0.12		$	0.40		$	0.62		$	1.21		$	0.19
Earnings (loss) per common share – basic – discontinued operations	—		0.21		—		—			—			(0.01		)	—			0.01
Earnings per common share – basic	$	0.45	$	0.61	$	1.42	$	0.12		$	0.40		$	0.61		$	1.21		$	0.20
Earnings per common share – diluted – continuing operations	$	0.45	$	0.40	$	1.41	$	0.12		$	0.40		$	0.62		$	1.20		$	0.19
Earnings (loss) per common share – diluted – discontinued operations	—		0.21		—		—			—			(0.01		)	—			0.01
Earnings per common share – diluted	$	0.45	$	0.61	$	1.41	$	0.12		$	0.40		$	0.61		$	1.20		$	0.20

(a) The sum of quarterly amounts, including per share amounts, may not equal amounts reported for year-to-date periods. This is because of the effects of rounding and the changes in the number of weighted-average diluted shares outstanding each period.

Ameren Missouri Quarter ended	Operating Revenues		Operating Income		Net Income  (Loss)			Net Income (Loss) Available to Common Shareholder
March 31, 2015	$	800	$	115	$	42		$	41
March 31, 2014	817		119		48			47
June 30, 2015	884		146		62			61
June 30, 2014	900		243		127			126
September 30, 2015	1,171		423		240			239
September 30, 2014	1,097		394		223			222
December 31, 2015	754		58		11			11
December 31, 2014	739		29		(5		)	(5		)

Ameren Illinois Quarter ended	Operating Revenues		Operating Income		Net Income		Net Income Available to Common Shareholder
March 31, 2015	$	745	$	120	$	54	$	53
March 31, 2014	774		120		54		53
June 30, 2015	513		83		32		31
June 30, 2014	519		75		29		28
September 30, 2015	655		189		98		98
September 30, 2014	572		158		75		75
December 31, 2015	553		74		33		32
December 31, 2014	633		97		46		45