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Collaborative Arrangements - Narrative (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development		$ 4,321	$ 2,085	$ 6,732	$ 4,260
Other liabilities, noncurrent		9,872		9,872		$ 12,306
Amortization				871	$ 988
Lynparza \| Other Assets
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Finite-lived intangible assets		1,200		1,200
Lenvima \| Other Assets
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Finite-lived intangible assets		1,000		1,000
Adempas \| Other intangible assets
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Finite-lived intangible assets		920		920
Verquvo
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Amortization				153
Verquvo \| Other intangible assets
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Finite-lived intangible assets		75		75
AstraZeneca \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement \| Lynparza
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential Future Milestone Payments Sales-Based		2,700		2,700
Milestone Payments Accrued Sales Based		400		400
Potential Future Milestone Payments Regulatory		1,400		1,400
Eisai
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
License option payment related to collaborative arrangement	$ 125
Eisai \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement \| Lenvima
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential Future Milestone Payments Sales-Based		2,600		2,600
Milestone Payments Sales-Based				200
Milestone Payments Accrued Sales Based		600		600
Potential Future Milestone Payments Regulatory		125		125
Bayer AG \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Liabilities		400		400
Milestone Payments Accrued Sales Based		$ 400		$ 400