XML 76 R65.htm IDEA: XBRL DOCUMENT v3.20.2

Accounting for Derivative Instruments and Hedging Activities - Net notional volume buy/sell of open derivative transactions (Details) shares in Millions, T in Millions, MWh in Millions, MMBTU in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2020 MMBTU MWh T shares	Dec. 31, 2019 MMBTU MWh T shares
Long | Emissions
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, mass (ton) | T	1	3
Long | Renewable Energy Certificates
Volumetric Underlying Derivative Transactions
Derivative, non-monetary notional amount (in shares) | shares	1	1
Long | Coal
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, mass (ton) | T	5	10
Long | Power
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, energy measure (MMBtu/MW/Day) | MWh	(56)	(38)
Short | Natural Gas
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, energy measure (MMBtu/MW/Day) | MMBTU	(237)	(181)
Short | Capacity
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, energy measure (MMBtu/MW/Day) | MMBTU	(1)	(1)

X

- Definition

Derivative, Non-monetary Notional Amount, Other

+ References

No definition available.

+ Details

Name:	nrg_DerivativeNonmonetaryNotionalAmountOther
Namespace Prefix:	nrg_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Volumetric Underlying Derivative Transactions [Abstract]

+ References

No definition available.

+ Details

Name:	nrg_VolumetricUnderlyingDerivativeTransactionsAbstract
Namespace Prefix:	nrg_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Nominal energy measure used to calculate payments on a derivative instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure
Namespace Prefix:	us-gaap_
Data Type:	num:energyItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Nominal mass used to calculate payments on a derivative instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeNonmonetaryNotionalAmountMass
Namespace Prefix:	us-gaap_
Data Type:	num:massItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_PositionAxis=us-gaap_LongMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_UnderlyingAssetClassAxis=nrg_EmissionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_UnderlyingAssetClassAxis=nrg_RenewableEnergyCertificatesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_UnderlyingAssetClassAxis=us-gaap_PublicUtilitiesInventoryCoalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_UnderlyingAssetClassAxis=nrg_PowerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_PositionAxis=us-gaap_ShortMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_UnderlyingAssetClassAxis=nrg_NaturalGasMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_UnderlyingAssetClassAxis=us-gaap_CapacityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: