LICENSE AGREEMENTS (Details) € in Thousands		1 Months Ended			3 Months Ended						6 Months Ended			12 Months Ended
	Jul. 30, 2020 USD ($)	Sep. 30, 2016 USD ($)	Aug. 31, 2016 USD ($)	Jun. 30, 2016 USD ($) option	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Mar. 31, 2021 EUR (€)	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2021 EUR (€)	Jun. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2020 EUR (€)
Organization And Basis Of Presentation [Line Items]
Royalty rate					2.00%						2.00%	2.00%
License and related revenue					$ 2,234,000					$ 0	$ 6,544,000		$ 0
Provision for income taxes					0					$ 0	$ 288,000		$ 0
Transaction price								$ 11,200,000	$ 11,200,000					$ 11,200,000
Qilu Pharmaceutical Co., Ltd. | Licensing Agreements
Organization And Basis Of Presentation [Line Items]
Potential milestone payments						$ 23,000,000
Total milestone payments	$ 23,000,000
Royalty payment based on annual net sales	12.00%
License and related revenue					$ 900,000	2,800,000			$ 11,200,000
Milestone payment						3,000,000
Outstanding payments						2,800,000
Cash payment	$ 12,000,000													12,000,000
University of Zurich
Organization And Basis Of Presentation [Line Items]
License agreement, royalty on net product sales, percentage											4.00%	4.00%
License agreement, rate requiring reduction in the amount of royalties owed											10.00%	10.00%
License agreement, royalty on net product sales, minimum											2.00%	2.00%
Expenses related to achievement of development milestone								300,000
University of Zurich | Collaborative Arrangement, Revenue Based on Clinical Development Milestone
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone											$ 500,000
Micromet AG
Organization And Basis Of Presentation [Line Items]
License agreement, royalty on net product sales, percentage											3.50%	3.50%
Expenses related to achievement of development milestone						600,000	€ 500							900,000	€ 700
Potential milestone payments											$ 2,900,000	€ 2,400
License Agreement, royalty payment, reduction, conditions not met											1.50%	1.50%
License maintenance fees											$ 59,420	€ 50
XOMA Ireland Limited
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone											$ 250,000
License agreement, royalty on net product sales, percentage											2.50%	2.50%
License agreement, rate requiring reduction in the amount of royalties owed											50.00%	50.00%
License agreement, royalty on net product sales, minimum											1.75%	1.75%
Roche
Organization And Basis Of Presentation [Line Items]
Up-front license fee			$ 7,500,000
Additional up-front fee			262,500,000
License agreement, option periods | option				2
License agreement, buyout amount under first option period				$ 135,000,000
License agreement, period to pay buyout option once exercised				30 days
License agreement, buyout amount under second option period				$ 265,000,000
License agreement, buyout amount under second option period, upon non-issuance of patent rights or licensed product				$ 220,000,000
Roche | First Indication
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone			197,500,000
Roche | Collaborative Arrangement, Revenue Based on Development Milestone
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone			72,500,000
Roche | Collaborative Arrangement, Revenue Based on Regulatory Milestone
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone			50,000,000
Roche | Collaborative Arrangement, Revenue Based on Commercialization Milestone
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone			75,000,000
Roche | Collaborative Arrangement, Revenue Based on Development Milestone, Phase II
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone			$ 20,000,000.0
Roche | Second Indication
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone											$ 65,000,000
Roche | EBI-031 | Minimum
Organization And Basis Of Presentation [Line Items]
Royalty rate					7.50%						7.50%	7.50%
Roche | EBI-031 | Maximum
Organization And Basis Of Presentation [Line Items]
Royalty rate					15.00%						15.00%	15.00%
Roche | EBI-031 | Collaborative Arrangement, Revenue Based on Development Milestone
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone		$ 22,500,000
Roche | IL-6
Organization And Basis Of Presentation [Line Items]
Royalty rate					50.00%						50.00%	50.00%
MENA License Agreement | Licensing Agreements
Organization And Basis Of Presentation [Line Items]
License and related revenue						1,500,000
Cash payment						$ 3,000,000
Transaction price								$ 1,500,000						$ 1,500,000
Percentage of upfront payment								0.50						0.50