Financial Instruments - Balance Sheet Grouping (Detail) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Selected financial assets	[1]	$ 38,157	$ 53,627
Selected financial liabilities	[1]	40,687	37,371
Cash and Cash Equivalents [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Selected financial assets		978	1,389
Short-term Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Selected financial assets		19,649	32,779
Long-term Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Selected financial assets		15,999	17,518
Other Current Assets [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Selected financial assets	[2]	587	1,059
Other Noncurrent Assets [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Selected financial assets	[3]	944	881
Short-Term Borrowings, including Current Portion of Long-term Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Selected financial liabilities		10,160	5,141
Other Current Liabilities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Selected financial liabilities	[4]	645	93
Long-term Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Selected financial liabilities		28,818	31,541
Other Noncurrent Liabilities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Selected financial liabilities	[5]	$ 1,064	$ 596

[1] We use a market approach in valuing financial instruments on a recurring basis. For additional information, see Note 1E. All of our financial assets and liabilities measured at fair value on a recurring basis use Level 2 inputs in the calculation of fair value, except less than 1% that use Level 1 inputs.

[2] As of December 31, 2015, derivative instruments at fair value include interest rate swaps ($2 million), foreign currency swaps ($46 million) and foreign currency forward-exchange contracts ($538 million) and, as of December 31, 2014, include interest rate swaps ($34 million), foreign currency swaps ($494 million) and foreign currency forward-exchange contracts ($531 million).

[3] As of December 31, 2015, derivative instruments at fair value include interest rate swaps ($835 million), foreign currency swaps ($89 million) and foreign currency forward-exchange contracts ($20 million) and, as of December 31, 2014, include interest rate swaps ($767 million), foreign currency swaps ($99 million) and foreign currency forward-exchange contracts ($15 million).

[4] At December 31, 2015, derivative instruments at fair value include interest rate swaps ($5 million), foreign currency swaps ($560 million) and foreign currency forward-exchange contracts ($80 million) and, as of December 31, 2014, include interest rate swaps ($1 million), foreign currency swaps ($13 million) and foreign currency forward-exchange contracts ($78 million).

[5] At December 31, 2015, derivative instruments at fair value include interest rate swaps ($134 million), foreign currency swaps ($928 million) and foreign currency forward-exchange contracts ($1 million) and, as of December 31, 2014, include interest rate swaps ($16 million) and foreign currency swaps ($581 million).