Goodwill an Other Intangibles (Tables)

12 Months Ended

Dec. 31, 2016

Goodwill and Other Intangibles Disclosure [Abstract]

Summary of the components of NRG's intangible assets subject to amortization

The following tables summarize the components of NRG's intangible assets subject to amortization:

				Contracts
Year Ended December 31, 2016	Emission Allowances			Energy Supply			Fuel			Customer			Customer Relationships			Marketing Partnerships			Trade Names			PPA			Other			Total
	(In millions)
January 1, 2016	$	920		$	54		$	72		$	16		$	834		$	88		$	342		$	1,264		$	245		$	3,835
Purchases	50			—			—			—			—			—			—			—			34			84
Acquisition of businesses	—			—			—			—			—			—			—			—			18			18
Usage	(1		)	—			—			—			—			—			—			—			(44		)	(45		)
Write-off of fully     amortized balances(a)	(10		)	—			—			—			—			—			—			—			—			(10		)
Impairment(b)	(23		)	—			—			—			(18		)	—			—			—			(23		)	(64		)
Other	(7		)	—			—			—			—			—			—			—			—			(7		)
December 31, 2016	929			54			72			16			816			88			342			1,264			230			3,811
Less accumulated amortization	(605		)	(54		)	(67		)	(8		)	(663		)	(49		)	(159		)	(138		)	(32		)	(1,775		)
Net carrying amount	$	324		$	—		$	5		$	8		$	153		$	39		$	183		$	1,126		$	198		$	2,036

(a) Adjusted for write-off of fully amortized emission allowances of $10 million.

(b) The impairment of customer relationships and other intangibles included a write-off of accumulated amortization of $10 million and $8 million respectively.

				Contracts
Year Ended December 31, 2015	Emission Allowances			Energy Supply			Fuel			Customer			Customer Relationships			Marketing Partnerships			Trade Names			PPA			Other			Total
	(In millions)
January 1, 2015	$	1,018		$	54		$	72		$	16		$	831		$	88		$	353		$	1,270		$	267		$	3,969
Purchases	77			—			—			—			3			—			—			—			57			137
Usage	(33		)	—			—			—			—			—			—			—			(62		)	(95		)
Write-off of fully amortized balances	(154		)	—			—			—			—			—			—			—			—			(154		)
Impairment	—			—			—			—			—			—			(6		)	—			(5		)	(11		)
Other	12			—			—			—			—			—			(5		)	(6		)	(12		)	(11		)
December 31, 2015	920			54			72			16			834			88			342			1,264			245			3,835
Less accumulated amortization(a)	(502		)	(47		)	(65		)	(6		)	(624		)	(41		)	(137		)	(75		)	(28		)	(1,525		)
Net carrying amount	$	418		$	7		$	7		$	10		$	210		$	47		$	205		$	1,189		$	217		$	2,310

(a) Adjusted for write-off of fully amortized emission allowances of $154 million.

Finite-lived Intangible Assets Amortization Expense [Table Text Block]

The following table presents NRG's amortization of intangible assets for each of the past three years:

	Years Ended December 31,
Amortization	2016		2015		2014
	(In millions)
Emission allowances	$	113	$	99	$	124
Energy supply contracts	7		5		6
Fuel contracts	2		2		2
Customer contracts	2		2		—
Customer relationships	49		67		70
Marketing partnerships	8		14		15
Trade names	22		23		21
Power purchase agreements	63		50		24
Other	12		15		6
Total amortization	$	278	$	277	$	268

Schedule of estimated amortization of NRG's intangible assets for each of the next five years

The following table presents estimated amortization of NRG's intangible assets for each of the next five years:

			Contracts
Year Ended December 31,	Emission Allowances		Fuel		Customer		Customer Relationships		Marketing Partnerships		Trade Names		PPA		Other		Total
	(In millions)
2017	$	82	$	1	$	1	$	26	$	5	$	23	$	57	$	3	$	198
2018	33		—		1		14		5		23		57		3		136
2019	31		—		1		10		4		23		57		3		129
2020	16		—		1		8		4		23		57		3		112
2021	16		—		1		6		4		23		57		3		110

Schedule of Out of Market Contracts, Future Amortization [Table Text Block]

The following table summarizes the estimated amortization related to NRG's out-of-market contracts:

Year Ended December 31,	Power Contracts		Leases	Gas Transportation		Total
	(In millions)
2017	$	16	47	$	37	$	100
2018	16		47	32		95
2019	17		47	29		93
2020	17		47	29		93
2021	10		47	26		83