Debt Instrument, Percent of Required Cash Collateral

No definition available.

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- Definition

Represents the net exposure of the entity determined as total credit exposure to all counterparties less collateral (cash and letters of credit) held against those positions as of the reporting date.

+ References

No definition available.

+ Details

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- Definition

Plan of Reorganization, Shared Services Agreement, Number of Optional Extensions

+ References

No definition available.

+ Details

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- Definition

Plan of Reorganization, Shared Services Agreement, Optional Extension Term

+ References

No definition available.

+ Details

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- Definition

Plan of Reorganization, Shared Services Agreement, Term

+ References

No definition available.

+ Details

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- Definition

Plan of Reorganization, Shares Services Agreement, Annualized Amount

+ References

No definition available.

+ Details

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Balance Type:	debit
Period Type:	duration

- Definition

Amount debtor-in-possession financing arranged (but not necessarily all borrowed).

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Amount of receivables due from an entity that is affiliated with the reporting entity by means of direct or indirect ownership, due within 1 year (or 1 business cycle).

+ References

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Balance Type:	debit
Period Type:	instant

- Definition

For an unclassified balance sheet, amounts due from related parties including affiliates, employees, joint ventures, officers and stockholders, immediate families thereof, and pension funds.

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Period Type:	instant

- Definition

Amount of payable due to an entity that is affiliated with the reporting entity by means of direct or indirect ownership. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Balance Type:	credit
Period Type:	instant

- Definition

Amount of interest income earned from interest-bearing assets owed to the entity by related party.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

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

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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-Publisher FASB
-Name Accounting Standards Codification
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+ Details

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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

+ Details

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

- Definition

Amounts due from parties associated with the reporting entity as evidenced by a written promise to pay, due within 1 year (or 1 business cycle).

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Balance Type:	debit
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- 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

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- Definition

The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc.

+ References

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-Name Accounting Standards Codification
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-SubTopic 10
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-Subparagraph (SX 210.5-03.4)
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Period Type:	duration

- Definition

The aggregate costs related to delivering management services during the reporting period.

+ References

+ Details

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

- Details

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Period Type:

- Details

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Balance Type:
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- Details

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- Details

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- Details

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- Details

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- Details

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Related Party Transactions (GenOn, GenOn Americas Generation and GenOn Mid-Atlantic) - Narrative (Details)	3 Months Ended		4 Months Ended	9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) extension	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)
Related Party Transaction
Net exposure under agreements	$ 47,000,000		$ 47,000,000	$ 47,000,000
NRG
Related Party Transaction
Transition services, annualized rate			$ 84,000,000
Transition services, period of services provided at no charge if settlement is approved			2 months
Transition services, number of optional extensions for services if settlement is approved \| extension			2
Transition services, Period of optional extensions for services if settlement is approved			1 month
NRG \| Senior Secured First Lien Notes, due 2022
Related Party Transaction
Credit against amount owed under shared services agreement upon emergence from bankruptcy	28,000,000		$ 28,000,000	28,000,000
GenOn Americas Generation
Related Party Transaction
Net exposure under agreements	47,000,000		47,000,000	47,000,000
NRG
Related Party Transaction
Annual fees under Services Agreement				193,000,000
Net exposure under agreements	0		0	0
NRG \| Intercompany Credit Agreement
Related Party Transaction
Maximum borrowing capacity	500,000,000		500,000,000	500,000,000
NRG \| Letter of Credit \| Intercompany Credit Agreement
Related Party Transaction
Letters of credit	103,000,000		103,000,000	103,000,000			$ 272,000,000
NRG \| Letter of Credit \| Restructuring Support Agreement, Letter of Credit Credit Facility
Related Party Transaction
Maximum borrowing capacity	330,000,000		$ 330,000,000	330,000,000
Percent of letters of credit provided required to be cash collateralized (as percent)			103.00%
NRG \| Restructuring Support Agreement, Credit Against Amounts Owed Prior to Petition Date Under Services Agreement
Related Party Transaction
Receivable from related party	28,000,000		$ 28,000,000	28,000,000		$ 28,000,000
NRG \| GenOn Americas Generation \| Letter of Credit \| Intercompany Credit Agreement
Related Party Transaction
Letters of credit	21,000,000		21,000,000	21,000,000			199,000,000
NRG \| GenOn Mid-Atlantic \| Letter of Credit \| Intercompany Credit Agreement
Related Party Transaction
Letters of credit	1,000,000		1,000,000	1,000,000			128,000,000
Loans outstanding	125,000,000		125,000,000	125,000,000			0
Affiliated Entity
Related Party Transaction
General and administrative	14,000,000	$ 46,000,000		100,000,000	$ 139,000,000
Affiliated Entity \| GenOn Americas Generation
Related Party Transaction
General and administrative	9,000,000	21,000,000		53,000,000	62,000,000
Note receivable	318,000,000		318,000,000	318,000,000			315,000,000
Affiliated Entity \| GenOn Mid-Atlantic
Related Party Transaction
General and administrative	4,000,000	$ 15,000,000		42,000,000	45,000,000
GenOn Energy Holdings \| GenOn Americas Generation
Related Party Transaction
Net interest income				0	$ 0
Accounts receivable - affiliate	50,000,000		50,000,000	50,000,000			77,000,000
Accounts payable - affiliate	$ 43,000,000		$ 43,000,000	$ 43,000,000			$ 43,000,000