v3.19.1

Derivative Instruments (Details 4) (Details) - USD ($)
$ in Millions

3 Months Ended

Mar. 31, 2019

Mar. 31, 2018

Summary of Derivative Instruments by Risk Exposure [Abstract]

Gain (Loss) on Derivative Instruments, Net, Pretax

^[1]

$ 156

$ (372)

Gain (Loss) on Sale of Derivatives

^[2],[3]

111

(3)

Mark-to-market gain (loss)

^[4]

45

(369)

Sales [Member]

Summary of Derivative Instruments by Risk Exposure [Abstract]

Gain (Loss) on Derivative Instruments, Net, Pretax

^[1],[5],[6]

37

(359)

Cost of Sales [Member]

Summary of Derivative Instruments by Risk Exposure [Abstract]

Gain (Loss) on Derivative Instruments, Net, Pretax

^[1],[5],[6]

120

(15)

Interest Expense [Member]

Summary of Derivative Instruments by Risk Exposure [Abstract]

Gain (Loss) on Derivative Instruments, Net, Pretax

^[1]

(1)

2

Interest Rate Hedging Instruments

Summary of Derivative Instruments by Risk Exposure [Abstract]

Mark-to-market gain (loss)

^[4]

(1)

2

Energy Related Derivative [Member]

Summary of Derivative Instruments by Risk Exposure [Abstract]

Gain (Loss) on Sale of Derivatives

^[2],[3]

111

(3)

Mark-to-market gain (loss)

^[4]

$ 46

$ (371)

[1]	In addition to changes in market value on derivatives not designated as hedges, changes in mark-to-market gain (loss) also includes adjustments to reflect changes in credit default risk exposure.
[2]	Does not include the realized value associated with derivative instruments that settle through physical delivery.
[3]	Includes amortization of acquisition date fair value of financial derivative activity related to the acquisition of Champion Energy, Calpine Solutions and North American Power.
[4]	In addition to changes in market value on derivatives not designated as hedges, changes in mark-to-market gain (loss) also includes adjustments to reflect changes in credit default risk exposure.
[5]	Does not include the realized value associated with derivative instruments that settle through physical delivery.
[6]	Includes amortization of acquisition date fair value of financial derivative activity related to the acquisition of Champion Energy, Calpine Solutions and North American Power.

X

- Definition

Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959

+ Details

Name:	us-gaap_GainLossOnDerivativeInstrumentsNetPretax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

The difference between the book value and the sale price of options, swaps, futures, forward contracts, and other derivative instruments. This element refers to the gain (loss) included in earnings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13(h))
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

+ Details

Name:	us-gaap_GainLossOnSaleOfDerivatives
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- References

No definition available.

+ Details

Name:	us-gaap_SummaryOfDerivativeInstrumentsByRiskExposureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

+ Details

Name:	us-gaap_UnrealizedGainLossOnDerivatives
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_SalesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_CostOfSalesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_InterestExpenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_EnergyRelatedDerivativeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: