Summary of Activity Related to Gross Unrecognized Tax Benefits (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Beginning Balance	$ 1,140	$ 1,188	$ 721
Increases related to prior year tax positions	77	37	222
Decreases related to prior year tax positions	(9)	(197)	(1)
Decreases related to settlement with tax authorities	(5)	(47)
Decreases as a result of a lapse of applicable statute of limitation		(97)
Increases related to current year tax positions	361	256	246
Ending Balance	$ 1,564	$ 1,140	$ 1,188

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The gross amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns as of the balance sheet date.

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The gross amount of decreases in unrecognized tax benefits resulting from tax positions taken in prior period tax returns, excluding amounts pertaining to examined tax returns.

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The gross amount of decreases in unrecognized tax benefits resulting from settlements with taxing authorities.

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The gross amount of increases in unrecognized tax benefits resulting from tax positions that have been or will be taken in the tax return for the current period, excluding amounts pertaining to examined tax returns.

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The gross amount of decreases in unrecognized tax benefits resulting from lapses of the applicable statutes of limitations.

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