Hedging Activities and Fair Value Measurements (Details) £ in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) Rate	Sep. 30, 2018 USD ($)	Sep. 30, 2019 GBP (£) units	Sep. 30, 2019 USD ($) units	Dec. 31, 2018 USD ($)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Payments for Hedge, Investing Activities			$ 294	$ 0
Derivative, Notional Amount						$ 9,487	$ 12,326
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax	$ 78	$ 45	136	105
Cost of Goods and Services Sold	777	672	2,265	2,084
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax	16	(1)	34	(20)
Interest Expense	95	58	294	177
Gain (Loss) on Derivative Used in Net Investment Hedge, after Tax	(9)	(8)	$ (25)	(13)
Derivative Asset, Fair Value, Gross Asset						504	304
Cash						249	133
Derivative Liability, Fair Value, Gross Liability						48	80
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Instrument, Fair Value Disclosure						11,990	7,239
Business Combination, Contingent Consideration, Liability						380	347
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount Rate, Fair Value Input			9.00%
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money Market Funds, at Carrying Value						26	13
Derivative Asset						504	304
Licensing arrangements, asset						633	0
Derivative Liability						48	80
Business Combination, Contingent Consideration, Liability						380	347
Licensing arrangements, liability						341	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure						768	427
Assets, Fair Value Disclosure						1,163	318
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money Market Funds, at Carrying Value						26	13
Derivative Asset						0	0
Licensing arrangements, asset						0	0
Derivative Liability						0	0
Business Combination, Contingent Consideration, Liability						0	0
Licensing arrangements, liability						0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure						0	0
Assets, Fair Value Disclosure						26	14
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money Market Funds, at Carrying Value						0	0
Derivative Asset						504	304
Licensing arrangements, asset						0	0
Derivative Liability						48	80
Business Combination, Contingent Consideration, Liability						0	0
Licensing arrangements, liability						0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure						48	80
Assets, Fair Value Disclosure						504	304
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money Market Funds, at Carrying Value						0	0
Derivative Asset						0	0
Licensing arrangements, asset						633	0
Derivative Liability						0	0
Business Combination, Contingent Consideration, Liability						380	347
Licensing arrangements, liability						341	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure						720	347
Assets, Fair Value Disclosure						633	0
Designated as Hedging Instrument [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Instruments in Hedges, Assets, at Fair Value						456	237
Derivative Instruments in Hedges, Liabilities, at Fair Value						$ 8	49
Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Forward Currency Contracts, Time to Maturity | units					60	60
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount						$ 3,522	5,880
Not Designated as Hedging Instrument [Member] | BTG Acquisition [Member] | Foreign Exchange Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Cash					£ 3,312	4,303
Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount						4,030	3,962
Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount						0	1,000
Net Investment Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount						1,935	1,483
Weighted Average [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount Rate, Fair Value Input			9.00%
Cost of Sales [Member] | Cash Flow Hedging [Member] | Foreign Exchange Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Foreign Currency Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months						104
Cost of Sales [Member] | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax	101	58	$ 176	135
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax	(23)	(13)	(40)	(30)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax	78	45	136	105
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	(22)	2	(47)	27
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, Tax	5	0	10	(6)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax	(17)	2	(36)	21
Interest Expense [Member] | Cash Flow Hedging [Member] | Interest Rate Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net						(5)
Interest Expense [Member] | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax	0		0	0
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax	0		0	0
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax	0		0	0
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	1		(3)	(1)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, Tax	0		(1)	0
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax	1		2	(1)
Interest Expense [Member] | Net Investment Hedging [Member] | Foreign Exchange Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Used in Net Investment Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net						48
Interest Expense [Member] | Net Investment Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other Comprehensive Income (Loss), Net Investment Hedge, Gain (Loss), before Reclassification and Tax	64	4	92	25
Other Comprehensive Income (Loss), Derivative, Excluded Component, Increase (Decrease), before Adjustments, Tax	(14)	(1)	(21)	(6)
Other Comprehensive Income (Loss), Derivative, Excluded Component, Increase (Decrease), before Adjustments, after Tax	50	3	71	19
Other Comprehensive Income (Loss), Net Investment Hedge, Gain (Loss), Reclassification, before Tax	(12)	(10)	(33)	(17)
Other Comprehensive Income (Loss), Net Investment Hedge, Gain (Loss), after Reclassification, Tax	3	2	7	4
Gain (Loss) on Derivative Used in Net Investment Hedge, after Tax	9	8	(25)	13
Other Nonoperating Income (Expense) [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	(202)	16	(334)	25
Foreign Currency Transaction Gain (Loss), before Tax	(4)	(23)	0	(40)
Net currency exchange gain (loss)	(207)	$ (6)	(334)	$ (15)
Other Nonoperating Income (Expense) [Member] | Not Designated as Hedging Instrument [Member] | BTG Acquisition [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	$ (207)		$ (323)
R&D, Regulatory and Commercialization-based Milestone [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration, Liability						220
R&D, Regulatory and Commercialization-based Milestone [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount Rate, Fair Value Input			3.00%
R&D, Regulatory and Commercialization-based Milestone [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount Rate, Fair Value Input			2.00%
R&D, Regulatory and Commercialization-based Milestone [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount Rate, Fair Value Input | Rate			3.00%
Prepaid Expenses and Other Current Assets [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Instruments in Hedges, Assets, at Fair Value						98	55
Prepaid Expenses and Other Current Assets [Member] | Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value						48	67
Other Noncurrent Assets [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Instruments in Hedges, Assets, at Fair Value						358	183
Other Current Liabilities [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Instruments in Hedges, Liabilities, at Fair Value						3	2
Other Current Liabilities [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Instruments in Hedges, Liabilities, at Fair Value						0	44
Other Current Liabilities [Member] | Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value						40	31
Other Noncurrent Liabilities [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Instruments in Hedges, Liabilities, at Fair Value						$ 5	$ 3