Income Taxes - Total Provision for Income Taxes (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current taxes:
Federal	$ (10)us-gaap_CurrentFederalTaxExpenseBenefit	$ (29)us-gaap_CurrentFederalTaxExpenseBenefit	$ (150)us-gaap_CurrentFederalTaxExpenseBenefit
State	1
Foreign	1,151us-gaap_CurrentForeignTaxExpenseBenefit	1,692us-gaap_CurrentForeignTaxExpenseBenefit	2,349us-gaap_CurrentForeignTaxExpenseBenefit
Current tax, net	1,142us-gaap_CurrentIncomeTaxExpenseBenefit	1,663us-gaap_CurrentIncomeTaxExpenseBenefit	2,199us-gaap_CurrentIncomeTaxExpenseBenefit
Deferred taxes:
Federal	961	509	596
State	(43)	44	10
Foreign	(423)	(292)	48
Deferred taxes, net	495us-gaap_DeferredIncomeTaxExpenseBenefit	261us-gaap_DeferredIncomeTaxExpenseBenefit	654us-gaap_DeferredIncomeTaxExpenseBenefit
Total	$ 1,637us-gaap_IncomeTaxExpenseBenefit	$ 1,924us-gaap_IncomeTaxExpenseBenefit	$ 2,853us-gaap_IncomeTaxExpenseBenefit

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