Contingencies - Deepwater Drilling Moratorium and Other Related Matters (Detail) (Disputed rig rental cost, contract-termination through March 2011 [Member], USD $)	Sep. 30, 2011
Disputed rig rental cost, contract-termination through March 2011 [Member]
Loss Contingencies [Line Items]
Maximum possible loss from contingency	$ 116,000,000
Loss contingency accrual at carrying value	$ 0

The estimated maximum amount of possible loss from the contingency.

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

-Publisher FASB

-Name Accounting Standards Codification

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-Section 50

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-Name FASB Interpretation (FIN)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

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-Section 50

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