Debt Instrument, Basis Spread on Libor Rate

No definition available.

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Balance Type:	na
Period Type:	instant

- Definition

Percentage of Ownership

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Incremental percentage increase (decrease) in the stated rate on a debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentInterestRateIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value of the amount outstanding under the credit facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13433-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13476-108611

+ Details

Name:	us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This element represents the current and noncurrent portions of a long-term real estate loan with an initial maturity beyond one year or beyond the normal operating cycle, if longer, to finance building costs. The funds are disbursed as needed or in accordance with a prearranged plan; generally, a portion of the funds is disbursed at inception and the remainder as construction progresses. The money is repaid on completion of the project (generally one to seven years), usually from the proceeds of a mortgage loan. The rate is normally higher than the prime rate, and there is usually an origination fee. The effective yield on these loans tends to be high, and the lender has a security interest in the real property.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19,20,22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

No definition available.

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash inflow from a borrowing with the highest claim on the assets of the entity in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle, if longer).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3255-108585

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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- Details

Name:	us-gaap_LongtermDebtTypeAxis=nrg_NonRecourseDebtMember
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Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_RevolvingCreditFacilityMember
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Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=nrg_CarlsbadFinancingAgreementMember
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Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_LetterOfCreditMember
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Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=nrg_WorkingCapitalFacilityMember
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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=nrg_TermLoanFacilityDue2023Member
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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
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- Details

Name:	us-gaap_VariableRateAxis=nrg_LondonInterbankOfferedRateLIBORfloorMember
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- Details

Name:	us-gaap_DebtInstrumentAxis=nrg_NRGYieldRevolvingCreditFacilityMember
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Balance Type:
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- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LetterOfCreditMember
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- Details

Name:	us-gaap_DebtInstrumentAxis=nrg_AguaCalienteBorrower1due2038Member
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- Details

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- Details

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Debt and Capital Leases - Narrative (Details) - USD ($)				3 Months Ended
Debt and Capital Leases - Narrative (Details) - USD ($)	Mar. 21, 2018	May 26, 2017	Feb. 17, 2017	Mar. 31, 2018	Apr. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt				$ 16,584,000,000		$ 16,633,000,000
Recourse Debt
Debt Instrument [Line Items]
Long-term debt				7,177,000,000		7,182,000,000
Non Recourse Debt
Debt Instrument [Line Items]
Long-term debt				9,407,000,000		9,451,000,000
Revolving Credit Facility \| Carlsbad Financing Agreement
Debt Instrument [Line Items]
Long-term construction loan		$ 194,000,000
Revolving Credit Facility \| Letter of Credit
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity		83,000,000
Revolving Credit Facility \| Working Capital Facility
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity		$ 4,000,000
Term loan facility, due 2023 \| Recourse Debt
Debt Instrument [Line Items]
Long-term debt				$ 1,867,000,000		1,872,000,000
Term loan facility, due 2023 \| Recourse Debt \| LIBOR
Debt Instrument [Line Items]
Change in interest rate	0.50%
Basis spread on variable rate	1.75%			1.75%
Term loan facility, due 2023 \| Recourse Debt \| LIBOR floor
Debt Instrument [Line Items]
Basis spread on variable rate	0.00%
NRG Yield Revolving Credit Facility
Debt Instrument [Line Items]
Borrowing outstanding under revolver				$ 75,000,000
NRG Yield Revolving Credit Facility \| Letter of Credit
Debt Instrument [Line Items]
Letters of credit outstanding under revolver				$ 67,000,000
NRG Yield Revolving Credit Facility \| Non Recourse Debt
Debt Instrument [Line Items]
Debt Instrument, Repurchase Amount				2.50%
Agua Caliente Borrower 1, due 2038 \| Non Recourse Debt
Debt Instrument [Line Items]
Percentage of ownership			51.00%
Proceeds from issuance of senior secured debt			$ 130,000,000
Interest rate, stated percentage			5.43%	5.43%
Long-term debt				$ 86,000,000		89,000,000
Carlsbad Energy Project \| Non Recourse Debt
Debt Instrument [Line Items]
Interest rate, stated percentage		4.12%
Proceeds from issuance of debt		$ 407,000,000
Long-term debt				475,000,000		$ 427,000,000
Carlsbad Energy Project \| Notes Payable
Debt Instrument [Line Items]
Long-term debt				$ 475,000,000
Subsequent Event \| NRG Yield Revolving Credit Facility \| Non Recourse Debt
Debt Instrument [Line Items]
Debt Instrument, Repurchase Amount					1.75%