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Collaboration Agreements - Deferred Revenue - Additional Information (Detail) - USD ($) $ in Thousands | Sep. 30, 2019 | Dec. 31, 2018
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Contract with Customer, Liability [Abstract] |  |
Deferred revenue | $ 53,988 | $ 0
AstraZeneca Agreements [Member] | China [Member] |  |
Contract with Customer, Liability [Abstract] |  |
Deferred revenue | $ 700 |

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- Definition Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=118944033&loc=SL49130531-203044 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 8 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130549-203045 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=118944033&loc=SL49130532-203044 + Details
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Balance Type: | credit
Period Type: | instant

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- References No definition available. + Details
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- Details
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Namespace Prefix: |
Data Type: | na
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- Details
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Namespace Prefix: |
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Balance Type: |
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