This item represents the amount of the total change in unrealized (holding) gains or losses for the period which are included in the statement of income. Such unrealized (holding) gains or losses relate to those assets and liabilities still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3).

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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.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

This element represents transfers out of assets and liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3) which have taken place during the period.

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- Definition

This element represents the net asset or liability measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances.

+ Details

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- Definition

This element represents total gains or losses for the period (realized and unrealized), arising from assets and liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in earnings or resulted in a change in net asset or liability value.

+ Details

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- Definition

This element represents total gains or losses for the period (realized and unrealized), arising from assets and liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in other comprehensive income (a separate component of shareholders' equity).

+ Details

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- Definition

This element represents purchases which have taken place during the period in relation to assets and liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3).

+ Details

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- Definition

This element represents settlements which have taken place during the period in relation to assets and liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3).

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- Definition

The change in assets and liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3) that occurred in the period due to a spin-off transaction.

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- Definition

This element represents a certain statement of financial position asset caption which represents a class of assets, or which may include an individual asset, measured at fair value on a recurring basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-Subparagraph a

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- Definition

This element represents a certain statement of financial position liability caption which represents a class of liabilities, or which may include an individual liability, measured at fair value on a recurring basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-Subparagraph a

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Fair Value Measurements (Details) (USD $) In Millions	3 Months Ended	9 Months Ended
Fair Value Measurements (Details) (USD $) In Millions	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative instruments, assets		$ 28		$ 172
Derivative instruments, liabilities				(105)
Reconciliation of net beginning and ending balances recorded for derivative instruments classified as Level 3 in the fair value hierarchy
Beginning balance, net Level 3 fair value asset (liability)	(3)	(2)	9
Total realized and unrealized gains (losses):
Included in net income	4		23
Included in other comprehensive income			4
Transfers to Level 2			(30)
Purchases			2
Settlements	1		(6)
Spin-off downstream businesses		2
Ending balance, net Level 3 fair value asset (liability)	2	0	2
Unrealized gains(losses) included in net income related to Level 3 derivative instruments	3		3
Fair Value, Inputs, Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative instruments, assets				58
Derivative instruments, liabilities				(102)
Fair Value, Inputs, Level 1 [Member] \| Commodity [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative instruments, assets				58
Derivative instruments, liabilities				(102)
Fair Value Inputs Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative instruments, assets		28		32
Fair Value Inputs Level 2 [Member] \| Interest rate [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative instruments, assets		28		32
Fair Value, Inputs, Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative instruments, assets				1
Derivative instruments, liabilities				(3)
Fair Value, Inputs, Level 3 [Member] \| Commodity [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative instruments, assets				1
Derivative instruments, liabilities				(3)
Fair Value (no inputs) Collateral [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative instruments, assets				81
Fair Value (no inputs) Collateral [Member] \| Commodity [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative instruments, assets				81
Commodity [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative instruments, assets				140
Derivative instruments, liabilities				(105)
Interest rate [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative instruments, assets		$ 28		$ 32