Collaboration Revenue - Changes in Balances of Receivables and Contract Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2020
Contract Liabilities:
Beginning balance		$ 202,305
Additions		1,293,370
Deductions		(53,401)
Ending balance	$ 1,442,274	1,442,274
Remaining performance obligations	104,945	104,945
Collaboration Revenue by Strategic Collaborator:
Contract Assets:
Beginning balance		1,972
Additions		115,037
Deductions		(85,354)
Ending balance	31,655	31,655
Contract Liabilities:
Beginning balance		199,528
Additions		117,002
Deductions		(50,320)
Ending balance	266,210	266,210
Amounts included in contract liabilities at the beginning of the period	13,263	50,320
Performance obligations satisfied (or partially satisfied) in previous reporting periods	0	1,262
Remaining performance obligations	$ 366,700	$ 366,700

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