Outstanding Oil Contracts That Are Not Designated For Hedge Accounting (Details) (Oil contracts [Member], USD $) In Millions, unless otherwise specified	Jun. 30, 2012
Outstanding contracts not designated for hedge accounting [Abstract]
Derivative Asset, Fair Value, Total	$ 104
Three Way collar contracts [Member]
Outstanding contracts not designated for hedge accounting [Abstract]
Derivative Asset, Fair Value, Total	104
Three Way collar contracts [Member] \| July 2012 - September 2012 [Member]
Outstanding contracts not designated for hedge accounting [Abstract]
Volume in MBbls	3,220
Additional Put Range Minimum	55.00
Additional Put Range Maximum	90.00
Derivative Weighted Average Additional Put Price	66.86
Floor Range Minimum	75.00
Floor Range Maximum	100.00
Derivative, Weighted Average Floor Price	82.96
Derivative Cap Price Minimum	88.20
Cap Range Maximum	137.80
Derivative, Weighted Average Cap Price	111.14
Derivative Asset, Fair Value, Total	8
Three Way collar contracts [Member] \| October 2012 - December 2012 [Member]
Outstanding contracts not designated for hedge accounting [Abstract]
Volume in MBbls	3,220
Additional Put Range Minimum	55.00
Additional Put Range Maximum	90.00
Derivative Weighted Average Additional Put Price	66.86
Floor Range Minimum	75.00
Floor Range Maximum	100.00
Derivative, Weighted Average Floor Price	82.96
Derivative Cap Price Minimum	88.20
Cap Range Maximum	137.80
Derivative, Weighted Average Cap Price	111.14
Derivative Asset, Fair Value, Total	10
Three Way collar contracts [Member] \| January 2013 - December 2013 [Member]
Outstanding contracts not designated for hedge accounting [Abstract]
Volume in MBbls	12,115
Additional Put Range Maximum	80.00
Derivative Weighted Average Additional Put Price	80.00
Floor Range Maximum	95.00
Derivative, Weighted Average Floor Price	95.00
Derivative Cap Price Minimum	106.50
Cap Range Maximum	130.40
Derivative, Weighted Average Cap Price	118.05
Derivative Asset, Fair Value, Total	62
Three Way collar contracts [Member] \| January 2014 - December 2014 [Member]
Outstanding contracts not designated for hedge accounting [Abstract]
Volume in MBbls	5,110
Additional Put Range Maximum	80.00
Derivative Weighted Average Additional Put Price	80.00
Floor Range Maximum	95.00
Derivative, Weighted Average Floor Price	95.00
Derivative Cap Price Minimum	117.50
Cap Range Maximum	120.75
Derivative, Weighted Average Cap Price	119.16
Derivative Asset, Fair Value, Total	$ 24

Additional Put Range Maximum

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- Definition

Additional Put Range Minimum.

+ References

No definition available.

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- Definition

Derivative Average Additional Put Price.

+ References

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- Definition

The cap rate (minimum price in a group of contracts) on a price risk derivative such as a cap or collar. A payment (receipt) is triggered if the market rate exceeds the cap rate on the contract.

+ References

No definition available.

+ Details

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- Definition

Floor rate (minimum price in a group of floor contracts) on a price risk derivative such as a floor or a collar. A payment (receipt) is triggered if the market rate falls below the floor rate on the contract.

+ References

No definition available.

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- Definition

The average cap rate on a group of price risk derivatives such as caps or collars. A payment or receipt is triggered if the market rate exceeds the cap rate on the contract.

+ References

No definition available.

+ Details

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- Definition

The average floor rate on a group of price risk derivatives such as floors or collars. A payment or receipt is triggered if the market rate falls below the floor rate on the contract.

+ References

No definition available.

+ Details

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- Definition

The cap rate on a price risk derivative such as a cap or collar. A payment or receipt is triggered if the market rate exceeds the cap rate on the contract.

+ References

No definition available.

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- Definition

Floor rate on a price risk derivative such as a floor or a collar. A payment or receipt is triggered if the market rate falls below the floor rate on the contract.

+ References

No definition available.

+ Details

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- Definition

Fair value as of the balance sheet date of derivative instrument not designated as hedging instrument and classified as an asset.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 107

-Paragraph 10

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (c)(2)

-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5624163-113959

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- Definition

Aggregate notional amount of price risk derivatives not designated as a hedging instrument with notional amounts expressed in nonmonetary units. For example the number of barrels specified in a fuel oil forward purchase contract.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Notional Amount

-URI http://asc.fasb.org/extlink&oid=6519104

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5579245-113959

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