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Financial Instruments and Risk Management - Financial Assets (Liabilities) Measured at Fair Value on Recurring Basis (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning Balance	$ 82
Other-than-temporary impairment charge and realized gains (losses) on financial assets	(318)
Transfer of senior debt floating rate notes	(5)
Settlement on Auction Rate Securities	(72)
Ending Balance
Amount of total losses for the period included in earnings attributable to assets still held at the reporting date	(5)
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other-than-temporary impairment charge and realized gains (losses) on financial assets	$ (5)

X

- Definition

Amount of total losses for the period included in earnings attributable to assets still held at the reporting date.

+ References

No definition available.

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- Definition

Settlement On Auction Rate Securities

+ References

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X

- Definition

Transfers out of liabilities measured at fair value and categorized within Level 3 of the fair value hierarchy that have taken place during the period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(3)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

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- Definition

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

+ References

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-Publisher FASB

-Name Accounting Standards Codification

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-Number 157

-Paragraph 32

-Subparagraph c

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- Definition

The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

+ References

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-Name FASB Staff Position (FSP)

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