Collaboration Agreements - Schedule of Accounts Receivable and Deferred Revenue Information, Antibody Collaboration (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Accounts receivable	$ 269,271	$ 193,684
Sanofi Collaboration Agreement, Antibody
Disaggregation of Revenue [Line Items]
Accounts receivable	187,704	121,001
Deferred revenue	$ 199,523	$ 117,682

Amount of receivables arising from transactions with related parties due within one year or the normal operating cycle, if longer.

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