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Summary of Significant Accounting Policies - Summary of Collaborators that Represent More Than 10% of Accounts Receivable (Details) - Customer Concentration Risk - Accounts receivable | 12 Months Ended
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Dec. 31, 2016 | Dec. 31, 2015
Janssen Biotech, Inc. (Janssen) |  |
Concentration Risk [Line Items] |  |
Percentage of significant accounts receivable | 40.00% | 39.00%
U.S. government |  |
Concentration Risk [Line Items] |  |
Percentage of significant accounts receivable | 19.00% | 20.00%
Les Laboratoires Servier and Institut de Reserches Servier (collectively, Servier) |  |
Concentration Risk [Line Items] |  |
Percentage of significant accounts receivable | 31.00% | 14.00%
Takeda |  |
Concentration Risk [Line Items] |  |
Percentage of significant accounts receivable |  | 14.00%
Eli Lilly |  |
Concentration Risk [Line Items] |  |
Percentage of significant accounts receivable |  | 13.00%

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