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Acquisitions, Divestitures, Research Collaborations and Licensing Agreements - Narrative (Details) $ in Millions |  | 1 Months Ended | 3 Months Ended | 6 Months Ended | 12 Months Ended |  |  |
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Jun. 02, 2021 | Dec. 31, 2024 USD ($) jurisdiction | Sep. 30, 2024 USD ($) | Jul. 31, 2024 USD ($) candidate aqua_facility | Mar. 31, 2024 USD ($) | Jun. 30, 2023 USD ($) | Jan. 31, 2023 USD ($) | Oct. 31, 2022 USD ($) | Aug. 31, 2022 USD ($) | Jul. 31, 2022 USD ($) | May 31, 2022 USD ($) | Mar. 31, 2025 USD ($) | Dec. 31, 2024 USD ($) jurisdiction | Dec. 31, 2025 USD ($) | Dec. 31, 2024 USD ($) jurisdiction | Dec. 31, 2023 USD ($) | Dec. 31, 2022 USD ($) | Apr. 30, 2024 candidate | Oct. 31, 2023 USD ($) antibodyDrugConjugate candidate | Feb. 28, 2023 USD ($) candidate
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Research and development |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 17,938 | $ 30,531 | $ 13,548 |  |  |
Sales |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 64,168 | 60,115 | 59,283 |  |  |
Cost of sales |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 15,193 | 16,126 | 17,411 |  |  |
Other current assets |  | $ 8,706 |  |  |  |  |  |  |  |  |  |  | $ 8,706 |  | 8,706 | 8,368 |  |  |  |
Accrued and other current liabilities |  | 15,694 |  |  |  |  |  |  |  |  |  |  | 15,694 |  | 15,694 | 15,766 |  |  |  |
Forecast | Subsequent Event |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Contingent consideration |  |  |  |  |  |  |  |  |  |  |  | $ 440 |  |  |  |  |  |  |  |
Royalty Pharma |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Compensation earned on arragement |  |  |  |  |  |  |  | $ 50 |  |  |  |  |  |  |  |  |  |  |  |
Related Party |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other current assets |  | 330 |  |  |  |  |  |  |  |  |  |  | 330 |  | 330 | 632 |  |  |  |
Accrued and other current liabilities |  | $ 113 |  |  |  |  |  |  |  |  |  |  | $ 113 |  | 113 | 598 |  |  |  |
Manufacturing and supply agreements | Related Party |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sales |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 392 | 394 | 383 |  |  |
Cost of sales |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 390 | 422 | 404 |  |  |
Minimum | Manufacturing and supply agreements | Related Party |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of continuing involvement after disposal | 4 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum | Manufacturing and supply agreements | Related Party |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of continuing involvement after disposal | 10 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discontinued Operations, Disposed of by Means Other than Sale, Spinoff | Organon & Co. |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of jurisdictions under interim operating agreement | jurisdiction |  | 1 |  |  |  |  |  |  |  |  |  |  | 1 |  | 1 |  |  |  |  |
Orion |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Eligible future contingent development-related payments (up to) |  |  |  | $ 30 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate, regulatory milestones payments, maximum |  |  |  | 625 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sales milestone payments |  |  |  | $ 975 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Orion | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Upfront payment made to collaborative partner |  |  |  |  |  |  |  |  |  | $ 290 |  |  |  |  |  |  |  |  |  |
Daiichi Sankyo | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Research and development |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 351 | 5,549 |  |  |  |
Number of antibody drug conjugates obtained right and obligations | antibodyDrugConjugate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 |
Accrued and other current liabilities |  | $ 817 |  |  |  |  |  |  |  |  |  |  | $ 817 |  | 817 | 800 |  |  |  |
Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Eligible future contingent development-related payments (up to) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 540 |
Aggregate, regulatory milestones payments, maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,500 |
Sales milestone payments |  |  |  |  |  |  |  |  |  |  | $ 780 |  |  |  |  |  |  |  | $ 3,100 |
Number of antibody drug conjugates | candidate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7
Upfront payment made to collaborative partner |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 175
Number of antibody drug conjugates terminated | candidate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 | 2 |
Number of exercised license option antibody drug conjugates | candidate |  |  |  | 1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of licensed antibody drug conjugates | candidate |  |  |  | 3 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of unexercised license option antibody drug conjugates | candidate |  |  |  | 1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payment resulting from the license option exercise |  |  |  | $ 38 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock investment in counterparty |  |  |  |  |  |  | $ 100 |  |  |  |  |  |  |  |  |  |  |  |  |
Option payment made to collaborative partner |  |  |  |  |  |  |  |  |  |  | 30 |  |  |  |  |  |  |  |  |
Milestone payment to be made to a collaborative partner |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 25 |  |  |  |
Contingent developmental milestone payments |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 90 |  |  |  |  |
Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | First Commercial Sale Milestones |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sales milestone payments |  |  |  |  |  |  |  |  |  |  | $ 290 |  |  |  |  |  |  |  |  |
Orna Therapeutics | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Eligible future contingent development-related payments (up to) |  |  |  |  |  |  |  |  | $ 440 |  |  |  |  |  |  |  |  |  |  |
Aggregate, regulatory milestones payments, maximum |  |  |  |  |  |  |  |  | 675 |  |  |  |  |  |  |  |  |  |  |
Sales milestone payments |  |  |  |  |  |  |  |  | 2,400 |  |  |  |  |  |  |  |  |  |  |
Preferred stock investment in counterparty |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 100 |  |  |
Upfront payment made to collaborative partner |  |  |  |  |  |  |  |  | $ 150 |  |  |  |  |  |  |  |  |  |  |
Elanco Animal Health Incorporated Aqua Business |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash paid for acquisition of business |  |  |  | $ 1,300 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Aqua manufacturing facilities | aqua_facility |  |  |  | 2 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
LM-299, LaNova Medicines Ltd |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration transferred, asset acquisition |  | 588 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum aggregate sales-based milestone payments |  | 1,400 |  |  |  |  |  |  |  |  |  |  | 1,400 |  | 1,400 |  |  |  |  |
Future contingent developmental milestone payments (up to) |  | 140 |  |  |  |  |  |  |  |  |  |  | 140 |  | 140 |  |  |  |  |
Future regulatory milestone payments (up to) |  | 860 |  |  |  |  |  |  |  |  |  |  | 860 |  | 860 |  |  |  |  |
LM-299, LaNova Medicines Ltd | Forecast |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Contingent consideration dependent upon technology transfer |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 300 |  |  |  |  |  |
CN201, Curon Biopharmaceutical |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration transferred, asset acquisition |  |  | $ 700 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Future contingent developmental milestone payments (up to) |  |  | 300 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Future regulatory milestone payments (up to) |  |  | 300 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Research and development |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 750 |  |  |  |  |
CN201, Curon Biopharmaceutical | Third-Party |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate contingent developmental, regulatory, and sales-based-related payments |  |  | $ 128 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Eyebiotech Limited |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration transferred, asset acquisition |  |  |  | $ 1,200 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum aggregate sales-based milestone payments |  |  |  | 500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Future contingent developmental milestone payments (up to) |  |  |  | 200 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Future regulatory milestone payments (up to) |  |  |  | 1,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Research and development |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,350 |  |  |  |  |
Transaction costs |  |  |  | 207 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Developmental milestone payment triggered and paid |  |  |  |  |  |  |  |  |  |  |  |  | 100 |  |  |  |  |  |  |
Net assets acquired |  |  |  | $ 21 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Harpoon Therapeutics, Inc. |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration transferred, asset acquisition |  |  |  |  | $ 765 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Research and development |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 656 |  |  |  |  |
Transaction costs |  |  |  |  | 56 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net assets acquired |  |  |  |  | $ 165 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Prometheus Biosciences, Inc. |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration transferred, asset acquisition |  |  |  |  |  | $ 11,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Research and development |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10,200 |  |  |  |
Net assets acquired |  |  |  |  |  | 877 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration transferred, to settle share-based equity awards |  |  |  |  |  | 1,200 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration transferred, to settle equity awards, unvested |  |  |  |  |  | 700 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash recorded for asset acquisition |  |  |  |  |  | 368 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investments recorded for asset acquisition |  |  |  |  |  | 296 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Deferred tax assets recorded for asset acquisition |  |  |  |  |  | 218 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other net liabilities recorded for asset acquisition |  |  |  |  |  | $ 5 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Imago BioSciences, Inc. |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration transferred, asset acquisition |  |  |  |  |  |  | 1,350 |  |  |  |  |  |  |  |  |  |  |  |  |
Research and development |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,200 |  |  |  |
Transaction costs |  |  |  |  |  |  | 60 |  |  |  |  |  |  |  |  |  |  |  |  |
Net assets acquired |  |  |  |  |  |  | $ 219 |  |  |  |  |  |  |  |  |  |  |  |  |
HS-10535 Hansoh Pharma |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration transferred, asset acquisition |  | 112 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum aggregate sales-based milestone payments |  | 1,470 |  |  |  |  |  |  |  |  |  |  | 1,470 |  | 1,470 |  |  |  |  |
Future contingent developmental milestone payments (up to) |  | 115 |  |  |  |  |  |  |  |  |  |  | 115 |  | 115 |  |  |  |  |
Future regulatory milestone payments (up to) |  | $ 315 |  |  |  |  |  |  |  |  |  |  | $ 315 |  | $ 315 |  |  |  |  |

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