Financial Instruments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Four Quarter Rolling Average of Notional Amount of Foreign Exchange Contracts Hedging Foreign Currency Transactions	$ 18,600		$ 18,600		$ 18,300
Description of Net Investment Hedge Activity			we have issued approximately €2.95 billion of euro-denominated long-term debt and €500 million of outstanding euro-denominated commercial paper borrowings, which qualify as a net investment hedge against our investments in European businesses. As of September 30, 2017, the net investment hedge is deemed to be effective.
Derivatives designated as hedging instruments, Asset Derivatives	295		$ 295		15
Derivatives not designated as hedging instruments, Asset Derivatives	95		95		155
Derivatives designated as hedging instruments, Liability Derivatives	15		15		196
Derivatives not designated as hedging instruments, Liability Derivatives	75		75		$ 158
Gain recorded in Accumulated other comprehensive loss	310	$ (7)	440	$ 188
Loss reclassified from Accumulated other comprehensive loss into Product Sales (effective portion)	(24)	32	(14)	139
Foreign Currency Cash Flow Hedge Loss to be Reclassified During Next 12 Months	80		$ 80
Maximum Length of Time, Foreign Currency Cash Flow Hedge			5 years 1 month 24 days
Gain recognized in Other income, net	$ 10	$ 19	$ 50	49
Payments for settlements of derivative contracts			$ 183	$ 29