BeiGene Agreement - Activity in Contract Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Movement in Deferred Revenue [Roll Forward]
Current deferred revenue	$ 638	$ 371
Collaboration and License Agreement
Movement in Deferred Revenue [Roll Forward]
Opening balance at beginning of period	(481)
Revenue from performance obligations satisfied during reporting period	108
Closing balance at end of period	$ (373)

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
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Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as current.

+ References

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-Publisher FASB
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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