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Acquisition, Collaborations and Other Arrangements - Collaborations and Other Arrangements (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
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Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017
Acquisition, Collaborations And Other Arrangements [Abstract] |  |  |  |
Initial consideration transferred | $ 284 | $ 0 | $ 304 | $ 0
Up-front collaboration expenses | $ 160 |  | $ 160 |

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- Definition Acquisition, Collaborations And Other Arrangements [Abstract] + References No definition available. + Details
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- Definition Revenue Collaboration Agreement, Initial Consideration Transferred + References No definition available. + Details
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- Definition Amount of other research and development expense. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 730 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6420194&loc=d3e21568-108373 + Details
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