Collaboration Agreements - Schedule of Changes in Contract Assets and Liabilities (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($)
Contract assets:
Accounts receivable, ADDITIONS	$ 847	[1]
Accounts receivable, BALANCE END OF PERIOD	847	[1]
Contract liabilities:
Deferred revenue, BALANCE BEGINNING OF PERIOD	62,697
Deferred revenue, DEDUCTIONS	(12,344)
Deferred revenue, BALANCE END OF PERIOD	$ 50,353

[1] Included in prepaid expenses and other current assets as shown within the condensed consolidated balance sheets.