Collaborations and Other Arrangements (Details) € / shares in Units, € in Millions, shares in Millions								1 Months Ended					3 Months Ended	12 Months Ended
	Dec. 21, 2021 USD ($)	Mar. 13, 2021 USD ($)	Aug. 25, 2020 USD ($)	Aug. 17, 2020 USD ($) program	Jul. 13, 2020 USD ($) shares	May 29, 2020 USD ($) shares	May 27, 2020	Jan. 31, 2021 USD ($)	Jan. 31, 2021 EUR (€)	Oct. 31, 2020 USD ($)	Aug. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($)	Mar. 31, 2021 USD ($) shares	Dec. 31, 2021 USD ($) shares	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($) shares	Dec. 31, 2014	Dec. 31, 2021 EUR (€) shares	Nov. 18, 2021 program	Apr. 30, 2021 USD ($)	Apr. 30, 2021 EUR (€)	Feb. 08, 2021	Dec. 15, 2020 EUR (€)	Jul. 17, 2020	Jun. 19, 2020	Aug. 31, 2019 € / shares	Jul. 31, 2018 USD ($)	Jan. 19, 2016 € / shares shares
Collaborative Arrangements
Acquired in-process research and development expenses														$ 177,000,000	$ 5,856,000,000	$ 4,251,000,000
Unrealized loss on investment of equity securities														610,000,000	1,700,000,000
Unrealized gain on investment of equity securities																1,200,000,000
Prepaid and other current assets														2,141,000,000	2,013,000,000
Other long-term assets														4,963,000,000	5,708,000,000
Cost of goods sold														6,601,000,000	4,572,000,000	4,675,000,000
Merck Sharp & Dohme Corp
Collaborative Arrangements
Percent of global and development and commercialization costs		60.00%
Revenues recognized														0
Option period to license certain inhibitors		5 years
Merck Sharp & Dohme Corp | Oral Formulation Product
Collaborative Arrangements
Net product sales threshold		$ 2,000,000,000
Percent of global product revenues		65.00%
Merck Sharp & Dohme Corp | Injectable Formulation Product
Collaborative Arrangements
Net product sales threshold		$ 3,500,000,000
Merck Sharp & Dohme Corp | Merck
Collaborative Arrangements
Percent of global and development and commercialization costs		40.00%
Arcus stock purchase agreement | Arcus
Collaborative Arrangements
Ownership percentage by noncontrolling owners																						19.50%
Janssen pharmaceuticals
Collaborative Arrangements
Purchase price of goods less specified amount, maximum percentage																	30.00%
Cost of goods sold														530,000,000	570,000,000	574,000,000
Period subject to termination																	10 years
Jounce license and stock purchase agreement | Jounce
Collaborative Arrangements
Ownership percentage by noncontrolling owners										14.00%
Japan tobacco
Collaborative Arrangements
Royalty expense														250,000,000	291,000,000	358,000,000
Cash paid												$ 559,000,000
Finite-lived intangible assets acquired												$ 550,000,000
Amortization useful life												9 years
Gadeta collaboration arrangement
Collaborative Arrangements
Noncontrolling interest in variable interest entity																82,000,000											$ 82,000,000
Other collaboration arrangements
Collaborative Arrangements
Cash payments made related to equity investments														147,000,000	72,000,000	118,000,000
Upfront collaboration expenses														177,000,000	129,000,000	331,000,000
Arcus
Collaborative Arrangements
Payments to acquire shares						$ 61,000,000
Shares of common stock acquired (in shares) | shares						2.2
Arcus | Arcus collaboration agreement and stock purchase agreements
Collaborative Arrangements
Payments to acquire in process research and development					$ 175,000,000
Additional shares acquired (in shares) | shares					6.0
Payments to acquire shares					$ 200,000,000
Total upfront payments made					391,000,000
Equity investment					135,000,000									559,000,000	212,000,000
Acquired in-process research and development expenses					256,000,000
Issuance discount (premium)					(65,000,000)
Direct transactional costs					16,000,000
Opt-in term							10 years
Number of clinical stage programs with exercise options | program																			3
Collaboration opt-in payments	$ 725,000,000
Research and development expenses														625,000,000
Unrealized gain on investment of equity securities														$ 127,000,000	80,000,000
Arcus | Arcus collaboration agreement
Collaborative Arrangements
Additional option fee on fourth, sixth, and eighth anniversaries					$ 100,000,000
Arcus | Arcus stock purchase agreement
Collaborative Arrangements
Payments to acquire shares													$ 220,000,000
Purchase period					5 years
Maximum percentage of outstanding stock allowed to be purchased					35.00%
Restriction period					3 years
Additional shares acquired (in shares) | shares													5.7
Number of shares (in shares) | shares														13.8				13.8
Pionyr
Collaborative Arrangements
Ownership percentage																									49.90%
Pionyr | Pionyr merger and option agreements
Collaborative Arrangements
Acquired in-process research and development expenses															215,000,000
Equity investments balance														$ 0	0
Payments to acquire equity method investments					$ 269,000,000
Estimated fair value					70,000,000
Option exercise fee					315,000,000
Maximum potential future milestone payments					1,200,000,000
Pionyr | Research and development service agreement
Collaborative Arrangements
Acquired in-process research and development expenses															80,000,000
Research and development future maximum payments					$ 115,000,000
Cash payments made for research and development milestones													$ 70,000,000
Tizona
Collaborative Arrangements
Ownership percentage																								49.90%
Tizona | Tizona merger and option agreements
Collaborative Arrangements
Acquired in-process research and development expenses															272,000,000
Equity investments balance														0	0
Payments to acquire equity method investments			$ 302,000,000
Estimated fair value			41,000,000
Option exercise fee			100,000,000
Tizona | Tizona merger and option agreements | Maximum
Collaborative Arrangements
Option fee and potential future milestone payments			$ 1,200,000,000
Tizona | Development agreement
Collaborative Arrangements
Acquired in-process research and development expenses															115,000,000
Tango | Tango collaboration and stock purchase agreement
Collaborative Arrangements
Payments to acquire in process research and development				$ 125,000,000
Payments to acquire shares				13,000,000
Acquired in-process research and development expenses				$ 125,000,000
Collaboration term				7 years
Cash payments made related to equity investments				$ 20,000,000
Number of programs | program				15
Tango | Tango collaboration and stock purchase agreement | Maximum
Collaborative Arrangements
Opt-in, extension and milestone payments				$ 410,000,000
Jounce | Jounce license and stock purchase agreement
Collaborative Arrangements
Total upfront payments made										$ 120,000,000
Acquired in-process research and development expenses														64,000,000
Cash payments made related to equity investments										$ 56,000,000
Future potential clinical, regulatory and commercial milestone payments														660,000,000
Galapagos | Filgotinib agreement
Collaborative Arrangements
Shares of common stock acquired (in shares) | shares																												6.8
Share price (in dollars per share) | € / shares																												€ 58
Galapagos | Amended 2019 agreement
Collaborative Arrangements
Payment of tiered royalties, low-end percentage																							8.00%
Payment of tiered royalties, high-end percentage																							15.00%
Potential payment for adjustments of budgeted development costs																190,000,000							€ 160
Payment for adjustments of budgeted development costs								$ 43,000,000	€ 35
Additional payment for adjustments of budgeted development costs in 2021																				$ 88,000,000	€ 75
Payment for adjustments of budgeted development costs in 2022														60,000,000				€ 50
Galapagos | Galapagos subscription agreement
Collaborative Arrangements
Additional shares acquired (in shares) | shares											2.6
Acquired in-process research and development expenses																$ 3,920,000,000
Shares of common stock acquired (in shares) | shares											6.8					16.7
Equity investments balance											$ 1,130,000,000			931,000,000
Unrealized loss on investment of equity securities														$ 717,000,000	1,800,000,000
Unrealized gain on investment of equity securities															1,200,000,000
Ownership percentage											25.80%
Share price (in dollars per share) | € / shares																										€ 140.59
Estimated fair value											$ 586,000,000
Payment for license and option rights											5,050,000,000.00
Issuance discount											$ 63,000,000
Maximum ownership percentage											29.90%
Standstill restricting term											10 years
Minimum ownership percentage											20.10%
Prepaid and other current assets															351,000,000
Other long-term assets															$ 1,300,000,000
Galapagos | Galapagos collaboration agreement
Collaborative Arrangements
Payment of tiered royalties, low-end percentage											20.00%
Payment of tiered royalties, high-end percentage											24.00%
Potential option exercise fee											$ 150,000,000