Financial Instruments and Risk Management (Details) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2015 USD ($) Debt_Instrument	Dec. 31, 2015 USD ($) Debt_Instrument	Dec. 31, 2014 USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, Noncurrent	$ 7,500	$ 7,500
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Fair value of marketable securities	96	$ 96	$ 103
Foreign Currency Derivatives [Abstract]
Maximum term of currency derivative instruments (in years)		1 year
Long-term Debt	15,346	$ 15,346	7,779
Long-term Debt, Current Maturities	$ (659)	$ (659)	(14)
Interest Rate Derivatives [Abstract]
Number of debt instruments with related interest rate swaps | Debt_Instrument	3	3
Floating rate basis		LIBOR-based
Weighted average floating rate (percentage)	4.00%	4.00%
Aggregate fixed rate debt after effect of interest rate swaps	$ 13,800	$ 13,800
Aggregate floating rate debt after effect of interest rate swaps	1,500	1,500
Long-term Debt, Excluding Current Maturities	14,687	14,687	7,765
Long-term Debt, Percentage Bearing Fixed Interest, Amount	$ 15,346	15,346	7,779
Available-for-sale Securities, Debt Maturities, Date	Jan. 29, 2018
Estimate of Fair Value, Fair Value Disclosure
Interest Rate Derivatives [Abstract]
Long-term debt	$ 15,956	15,956	9,079
Estimate of Fair Value, Fair Value Disclosure | Level 1
Interest Rate Derivatives [Abstract]
Long-term debt	1,009	1,009	4,822
Estimate of Fair Value, Fair Value Disclosure | Level 2
Interest Rate Derivatives [Abstract]
Long-term debt	14,947	14,947	4,257
Carrying (Reported) Amount, Fair Value Disclosure
Foreign Currency Derivatives [Abstract]
Long-term Debt	15,346	15,346
Interest Rate Derivatives [Abstract]
Long-term Debt, Excluding Current Maturities			7,779
Other current assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale securities, current	63	63	56
Other assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale securities, noncurrent	33	33	47
Interest Rate Swap [Member]
Foreign Currency Derivatives [Abstract]
Derivative, Notional Amount	1,500	1,500
Foreign Exchange Contract [Member]
Foreign Currency Derivatives [Abstract]
Derivative, Notional Amount	$ 619	$ 619	$ 662
UNITED STATES | Geographic Concentration Risk | Accounts Receivable
Interest Rate Derivatives [Abstract]
Concentration Risk, Percentage (in hundredths)			39.00%