XML 113 R83.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Fair Value of Financial Instruments - Derivative Fair Value Measurements Narrative (Details) - USD ($) $ in Millions | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Fair Value Disclosures [Abstract] |  |
Total derivative assets valued with prices provided by models and other valuation techniques percentage | 6.00% |
Total derivative liabilities valued with prices provided by models and other valuation techniques, percentage | 10.00% |
Increase (decrease) in credit reserve |  | $ 10

X
- Definition This element represents the portion of total fair value of all derivative assets, which are valued using various valuation techniques including internal models based on a fundamental analysis of the market and extrapolation of observable market data with similar characteristics. + References No definition available. + Details
Name: | nrg_DerivativeAssetFairValueDeterminedUsingValuationTechniquesPercentage
Namespace Prefix: | nrg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Derivative Liability, Fair Value Determined Using Valuation Techniques, Percentage + References No definition available. + Details
Name: | nrg_DerivativeLiabilityFairValueDeterminedUsingValuationTechniquesPercentage
Namespace Prefix: | nrg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_FairValueDisclosuresAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690 + Details
Name: | us-gaap_ValuationAllowancesAndReservesBalance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant