Collaboration and Other Agreements - Zai Lab (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Nov. 30, 2018	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Collaboration And Other Agreements [Line Items]
Revenues		$ 16,881	$ 13,682
Zai Lab Agreement \| Zai Labs
Collaboration And Other Agreements [Line Items]
Non-refundable upfront payment	$ 25,000
Non-refundable upfront payment, net of tax withholding	22,500
Nonrefundable payment tax withholding	$ 2,500
Potential development and regulatory milestone payments under agreement			140,000
Revenues			4,000
Revenues, Net Of Tax Withholding			3,600
Revenues, Tax Withholding			400
Deferred revenue		0		$ 0
Zai Lab Clinical Supply Agreements \| Zai Labs
Collaboration And Other Agreements [Line Items]
Revenues		$ 1,100	$ 1,000
Zai Lab Agreement, Margetuximab \| Zai Labs \| Maximum
Collaboration And Other Agreements [Line Items]
Potential proceeds from royalties (percent)	20.00%
Zai Lab Agreement, TRIDENT molecule \| Zai Labs
Collaboration And Other Agreements [Line Items]
Potential proceeds from royalties (percent)	10.00%