Guarantees - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Guarantor Obligations
Guarantee obligation	$ 4,602	$ 1,746
Letters of credit and surety bonds
Guarantor Obligations
Guarantee obligation	$ 4,095	1,153
Letters of credit and surety bonds, maximum expiration period (in years)	1 year
Asset sales guarantee obligations
Guarantor Obligations
Guarantee obligation	$ 414	$ 506
California property tax indemnity	$ 158

The estimated amount of future payments the guarantor could be required to make under guarantees, indemnities and other contingent liability obligations.

No definition available.

+ Details

Name:	nrg_GuaranteeObligationsEstimatedExposure
Namespace Prefix:	nrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This element represents the maximum expiration period of letters of credit and surety bonds for entity is contingently obliged.

+ References

No definition available.

+ Details

Name:	nrg_GuaranteeObligationsLettersofCreditandSuretyBondsMaximumExpirationPeriod
Namespace Prefix:	nrg_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=124440162&loc=d3e12069-110248

+ Details

Name:	us-gaap_GuaranteeObligationsCurrentCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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_GuaranteeObligationsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_GuaranteeObligationsByNatureAxis=nrg_LettersOfCreditAndSuretyBondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_GuaranteeObligationsByNatureAxis=nrg_AssetSalesGuaranteeObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: