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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
	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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