Unaudited Quarterly Financial Data (Tables)

12 Months Ended

Dec. 31, 2014

Quarterly Financial Information Disclosure [Abstract]

Summary of Unaudited Quarterly Financial Data

Summarized unaudited quarterly financial data is as follows:

	Quarter Ended
	2014
	December 31		September 30		June 30			March 31
	(In millions, except per share data)
Operating revenues	$	4,192	$	4,569	$	3,621		$	3,486
Operating income	453		549		89			180
Net income/(loss)	97		182		(80		)	(67		)
Net income/(loss) attributable to NRG Energy, Inc.	$	119	$	168	$	(97	)	$	(56	)
Weighted average number of common shares outstanding — basic	338		338		337			324
Net income/(loss) per weighted average common share — basic	$	0.21	$	0.49	$	(0.30	)	$	(0.18	)
Weighted average number of common shares outstanding — diluted	342		343		337			324
Net income/(loss) per weighted average common share — diluted	$	0.20	$	0.48	$	(0.30	)	$	(0.18	)

	Quarter Ended
	2013
	December 31			September 30		June 30		March 31
	(In millions, except per share data)
Operating revenues	$	2,795		$	3,490	$	2,929	$	2,081
Operating (loss)/income	(205		)	527		287		(266		)
Net (loss)/income	(290		)	138		131		(331		)
Net (loss)/income attributable to NRG Energy, Inc.	$	(297	)	$	119	$	124	$	(332	)
Weighted average number of common shares outstanding — basic	323			323		323		323
Net (loss)/income per weighted average common share — basic	$	(0.92	)	$	0.36	$	0.37	$	(1.03	)
Weighted average number of common shares outstanding — diluted	323			327		327		323
Net (loss)/income per weighted average common share — diluted	$	(0.92	)	$	0.36	$	0.37	$	(1.03	)