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Summary of Significant Accounting Policies - Summary of Collaborators that Represent More Than 10% of Total Revenue Earned and Accounts Receivable (Details) - Customer Concentration Risk | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Sales revenue, net | Incyte Corporation (Incyte) |  |  |
Concentration Risk [Line Items] |  |  |
Percentage of significant accounts receivable | 35.00% | 68.00% | 96.00%
Sales revenue, net | Zai Lab Limited (Zai Lab) |  |  |
Concentration Risk [Line Items] |  |  |
Percentage of significant accounts receivable | 29.00% |  |
Sales revenue, net | Les Laboratoires Servier and Institut de Recherches Servier (Servier) |  |  |
Concentration Risk [Line Items] |  |  |
Percentage of significant accounts receivable | 18.00% |  |
Accounts receivable | Incyte Corporation (Incyte) |  |  |
Concentration Risk [Line Items] |  |  |
Percentage of significant accounts receivable | 62.00% | 16.00% |
Accounts receivable | Zai Lab Limited (Zai Lab) |  |  |
Concentration Risk [Line Items] |  |  |
Percentage of significant accounts receivable | 23.00% | 76.00% |

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