Goodwill and Other Intangible Assets - Other Intangible Assets Amortization Expense Table (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 1,037	$ 229
Accumulated amortization	(44)	(59)
Net carrying amount	993us-gaap_FiniteLivedIntangibleAssetsNet	170us-gaap_FiniteLivedIntangibleAssetsNet
Amortization expense	6us-gaap_AmortizationOfIntangibleAssets	7us-gaap_AmortizationOfIntangibleAssets
Offshore Platform Leases [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	33	60
Accumulated amortization	(29)	(50)
Net carrying amount	4	10
Amortization expense	0	3
Customer Contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	1,004	169
Accumulated amortization	(15)	(9)
Net carrying amount	989	160
Amortization expense	$ 6	$ 4

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 45

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-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274

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

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-Name Accounting Standards Codification

-Topic 350

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-Section 50

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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