Financial Instruments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivatives designated as hedging instruments, Asset Derivatives	$ 212		$ 178
Derivatives not designated as hedging instruments, Asset Derivatives	129		75
Derivatives designated as hedging instruments, Liability Derivatives	26		18
Derivatives not designated as hedging instruments, Liability Derivatives	46		60
Four Quarter Rolling Average of Notional Amount of Foreign Exchange Contracts Hedging Foreign Currency Transactions	$ 20,700		19,100
Description of Net Investment Hedge Activity	we have approximately €2.95 billion of euro-denominated long-term debt and €750 million of euro-denominated commercial paper borrowings outstanding, which qualify as a net investment hedge against our investments in European businesses. As of March 31, 2018, the net investment hedge is deemed to be effective.
Gain recorded in Accumulated other comprehensive loss	$ 45	$ 64
Loss reclassified from Accumulated other comprehensive loss into Product Sales (effective portion)	$ (27)	5
Maximum Length of Time, Foreign Currency Cash Flow Hedge	4 years 22 days
Gain recognized in Other income, net	$ 51	12
Payments for settlements of derivative contracts	221	$ 113
Foreign Currency Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months	36
Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives designated as hedging instruments, Asset Derivatives	90		77
Derivatives not designated as hedging instruments, Asset Derivatives	123		70
Other Noncurrent Assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives designated as hedging instruments, Asset Derivatives	122		101
Derivatives not designated as hedging instruments, Asset Derivatives	6		5
Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives designated as hedging instruments, Liability Derivatives	10		10
Derivatives not designated as hedging instruments, Liability Derivatives	42		57
Other Long-term Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives designated as hedging instruments, Liability Derivatives	16		8
Derivatives not designated as hedging instruments, Liability Derivatives	$ 4		$ 3