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Acquisitions, Research Collaborations and License Agreements - Acquisitions (Details) - USD ($) $ in Millions |  | 1 Months Ended | 3 Months Ended | 6 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | --- | ---
Jan. 16, 2020 | Apr. 30, 2021 | Mar. 31, 2021 | Jan. 31, 2021 | Dec. 31, 2020 | Jun. 30, 2020 | Jun. 30, 2021 | Jun. 30, 2020 | Jun. 30, 2021 | Jun. 30, 2020 | Dec. 31, 2020 | Dec. 31, 2019
Acquisitions Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Contingent consideration |  |  |  |  | $ 841.0 | $ 798.0 | $ 879.0 | $ 798.0 | $ 879.0 | $ 798.0 | $ 841.0 | $ 767.0
Goodwill |  |  |  |  | 18,882.0 |  | 18,873.0 |  | 18,873.0 |  | 18,882.0 |
Research and development |  |  |  |  |  |  | 4,321.0 | 2,085.0 | 6,732.0 | 4,260.0 |  |
Inventories |  |  |  |  | 5,554.0 |  | 5,499.0 |  | 5,499.0 |  | 5,554.0 |
Payments to Acquire Productive Assets |  |  |  |  |  |  |  |  | 2,068.0 | 1,553.0 |  |
Changes in estimated fair value |  |  |  |  |  |  |  |  | 50.0 | 40.0 |  |
OncoImmune |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Payment to acquire business |  |  |  |  | 423.0 |  |  |  |  |  |  |
Other assets and liabilities, net |  |  |  |  | (22.0) |  |  |  |  |  | $ (22.0) |
Payments to Acquire Investments |  |  |  |  | $ 50.0 |  |  |  |  |  |  |
Equity Method Investment, Ownership Percentage |  |  |  |  | 20.00% |  |  |  |  |  | 20.00% |
Investments |  |  |  |  | $ 33.0 |  |  |  |  |  | $ 33.0 |
Premium on shares acquired |  |  |  |  | $ 17.0 |  |  |  |  |  |  |
Research and Development Asset Acquired Other than Through Business Combination, Written-off |  |  |  |  |  |  |  |  |  |  | 462.0 |
COVID-19 |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Charges related to program discontinuation |  |  |  |  |  |  | $ 37.0 |  | $ 207.0 |  |  |
Pandion Therapeutics |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Payment to acquire business |  | $ 1,900.0 |  |  |  |  |  |  |  |  |  |
Transaction costs |  | 147.0 |  |  |  |  |  |  |  |  |  |
Other assets and liabilities, net |  | (156.0) |  |  |  |  |  |  |  |  |  |
Research and development |  | $ 1,700.0 |  |  |  |  |  |  |  |  |  |
Themis |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Payment to acquire business |  |  |  |  |  | 366.0 |  |  |  |  |  |
Contingent consideration |  |  |  |  |  | 85.0 |  | 85.0 |  | 85.0 |  |
IPR&D |  |  |  |  |  | 113.0 |  | 113.0 |  | 113.0 |  |
Cash and cash equivalents |  |  |  |  |  | 59.0 |  | 59.0 |  | 59.0 |  |
Goodwill |  |  |  |  |  | 239.0 |  | 239.0 |  | 239.0 |  |
Other assets and liabilities, net |  |  |  |  |  | (32.0) |  | (32.0) |  | (32.0) |  |
Deferred tax assets |  |  |  |  |  | 72.0 |  | 72.0 |  | 72.0 |  |
Contingent consideration, maximum |  |  |  |  |  | 740.0 |  | 740.0 |  | 740.0 |  |
Business Combination, Contingent Consideration Arrangements, Change in Range of Outcomes, Contingent Consideration, Liability, Value, High |  |  |  |  |  |  |  |  |  |  | 450.0 |
Themis | COVID-19 |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill) |  |  |  |  |  |  |  |  |  |  | 90.0 |
Changes in estimated fair value |  |  |  |  |  |  |  |  |  |  | $ 45.0 |
ArQule |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Payment to acquire business | $ 2,700.0 |  |  |  |  |  |  |  |  |  |  |
IPR&D | 2,280.0 |  |  |  |  |  |  |  |  |  |  |
Share-based compensation payments attributable to precombination service | 138.0 |  |  |  |  |  |  |  |  |  |  |
Transaction costs | 95.0 |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | 145.0 |  |  |  |  |  |  |  |  |  |  |
Goodwill | 512.0 |  |  |  |  |  |  |  |  |  |  |
Other assets and liabilities, net | 34.0 |  |  |  |  |  |  |  |  |  |  |
Deferred income tax liabilities | 361.0 |  |  |  |  |  |  |  |  |  |  |
Intangible assets | $ 80.0 |  |  |  |  |  |  |  |  |  |  |
Development Milestones | Themis |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Contingent consideration, maximum |  |  |  |  |  | 60.0 |  | 60.0 |  | 60.0 |  |
Sales-Based Milestones | Themis |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Contingent consideration, maximum |  |  |  |  |  | 194.0 |  | 194.0 |  | 194.0 |  |
Regulatory Milestones | Themis |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Contingent consideration, maximum |  |  |  |  |  | $ 196.0 |  | $ 196.0 |  | $ 196.0 |  |
Gilead Sciences | oral and injectable formulations programs | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
proft share |  |  | 40.00% |  |  |  |  |  |  |  |  |
profit share counterparty |  |  | 60.00% |  |  |  |  |  |  |  |  |
Gilead Sciences | oral formulation | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
proft share |  |  | 35.00% |  |  |  |  |  |  |  |  |
profit share counterparty |  |  | 65.00% |  |  |  |  |  |  |  |  |
Sales threshold |  |  | $ 2,000.0 |  |  |  |  |  |  |  |  |
Gilead Sciences | injectable formulation | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
proft share |  |  | 35.00% |  |  |  |  |  |  |  |  |
profit share counterparty |  |  | 65.00% |  |  |  |  |  |  |  |  |
Sales threshold |  |  | $ 3,500.0 |  |  |  |  |  |  |  |  |
Artiva Biotherapeutics, Inc. | Licensing Agreements |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Upfront and milestone payments |  |  |  | $ 30.0 |  |  |  |  |  |  |  |
Upfront and milestone payments to be made |  |  |  | $ 15.0 |  |  |  |  |  |  |  |
Artiva Biotherapeutics, Inc. | Minimum | Licensing Agreements |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Royalty Rate, Percentage |  |  |  | 7.00% |  |  |  |  |  |  |  |
Artiva Biotherapeutics, Inc. | Maximum | Licensing Agreements |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Royalty Rate, Percentage |  |  |  | 14.00% |  |  |  |  |  |  |  |
Artiva Biotherapeutics, Inc. | Development Milestones | Licensing Agreements |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Contingent milestone payments collaborative arrangement |  |  |  | $ 217.5 |  |  |  |  |  |  |  |
Artiva Biotherapeutics, Inc. | Sales-Based Milestones | Licensing Agreements |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Contingent milestone payments collaborative arrangement |  |  |  | 1,050.0 |  |  |  |  |  |  |  |
Artiva Biotherapeutics, Inc. | Regulatory Milestones | Licensing Agreements |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Contingent milestone payments collaborative arrangement |  |  |  | $ 570.0 |  |  |  |  |  |  |  |

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