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Name:	us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Collaborative and Licensing Arrangements - BioAtla, Inc. (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Apr. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Research and development collaborative arrangements
Research and Development in Process		$ 109,500	$ 69,000	$ 70,000
BioAtla, Inc. \| Collaborative arrangement \| CAB-CTLA-4
Research and development collaborative arrangements
Research and Development in Process	$ 20,000