Financial Instruments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Derivatives designated as hedging instruments, Asset Derivatives	$ 35		$ 35		$ 22
Derivatives not designated as hedging instruments, Asset Derivatives	86		86		63
Derivatives designated as hedging instruments, Liability Derivatives	149		149		194
Derivatives not designated as hedging instruments, Liability Derivatives	82		82		92
Four Quarter Rolling Average of Notional Amount of Foreign Exchange Contracts Hedging Foreign Currency Transactions	18,200		$ 18,200		20,100
Description of Net Investment Hedge Activity			We have €4.95 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 June 30, 2019, the net investment hedge is deemed to be effective.
Gain (loss) recorded in Accumulated other comprehensive loss	21	$ (245)	$ 28	$ (200)
(Gain) loss reclassified from Accumulated other comprehensive loss into Product Sales (effective portion)	16	(1)	$ 20	(28)
Maximum Length of Time, Foreign Currency Cash Flow Hedge			4 years 22 days
Gain recognized in Other income, net	18	$ 19	$ 36	$ 70
Foreign Currency Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months	(23)		(23)
Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives designated as hedging instruments, Asset Derivatives	16		16		10
Derivatives not designated as hedging instruments, Asset Derivatives	79		79		44
Other Noncurrent Assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives designated as hedging instruments, Asset Derivatives	19		19		12
Derivatives not designated as hedging instruments, Asset Derivatives	7		7		19
Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives designated as hedging instruments, Liability Derivatives	59		59		83
Derivatives not designated as hedging instruments, Liability Derivatives	80		80		89
Other Long-term Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives designated as hedging instruments, Liability Derivatives	90		90		111
Derivatives not designated as hedging instruments, Liability Derivatives	$ 2		$ 2		$ 3