LICENSE AGREEMENTS (Details) $ in Thousands			1 Months Ended		2 Months Ended	3 Months Ended			12 Months Ended
	Jul. 30, 2020 USD ($)	Jun. 10, 2016 USD ($) indication option	Sep. 30, 2020 USD ($)	Aug. 31, 2016 USD ($)	Sep. 15, 2016 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2020 EUR (€)	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2020 EUR (€)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Organization And Basis Of Presentation [Line Items]
License agreement, royalty rate						2.00%			2.00%
Provision for Income Taxes									$ 1,445		$ 0	$ 0
Total revenue									11,236		0	$ 0
Deferred revenue, current						$ 1,500			1,500		$ 0
Qilu Pharmaceutical Co., Ltd.
Organization And Basis Of Presentation [Line Items]
Net proceeds			$ 10,000
Qilu Pharmaceutical Co., Ltd. | Licensing Agreements
Organization And Basis Of Presentation [Line Items]
Upfront payment	$ 12,000		12,000
Total milestone payments	$ 23,000
Royalty payment, percentage	12.00%
Transaction price			$ 11,200					$ 11,200
Provision for Income Taxes									$ 1,100
Total revenue								$ 11,200
Micromet AG
Organization And Basis Of Presentation [Line Items]
Royalty payment obligation, percent									3.50%	3.50%
Expenses related to achievement of development milestone | €							€ 700,000
Potential milestone payments | €										€ 2,900,000
License agreement, royalty payment, reduction, conditions not met									1.50%	1.50%
License maintenance fees | €										€ 50,000
XOMA Ireland Limited
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone									$ 250
Royalty payment obligation, percent									2.50%	2.50%
Third party maximum ownership, percent									50.00%	50.00%
Third party minimum ownership, percent									1.75%	1.75%
Roche
Organization And Basis Of Presentation [Line Items]
License agreement, up-front fee				$ 7,500
License agreement, additional up-front fee				262,500
License agreement, number of unrelated Indications | indication		2
License agreement, option periods | option		2
License agreement, buyout amount under first option period		$ 135,000
License agreement, period to pay buyout option once exercised		30 days
License agreement, buyout amount under second option period		$ 265,000
License agreement, buyout amount under second option period, upon non-issuance of patent rights or licensed product		$ 220,000
License agreement, period for termination where sufficient development activities are not performed		12 months
Roche | EBI-031 | Minimum
Organization And Basis Of Presentation [Line Items]
License agreement, royalty rate		7.50%
Roche | EBI-031 | Maximum
Organization And Basis Of Presentation [Line Items]
License agreement, royalty rate		15.00%
Roche | IL-6
Organization And Basis Of Presentation [Line Items]
License agreement, royalty rate		50.00%
MENA License Agreement
Organization And Basis Of Presentation [Line Items]
Net proceeds									$ 2,700
Deferred revenue						3,000			3,000
Deferred revenue, current						1,500			1,500
MENA License Agreement | Licensing Agreements
Organization And Basis Of Presentation [Line Items]
Upfront payment									3,000
Transaction price						1,500			1,500
Provision for Income Taxes									$ 300
University of Zurich
Organization And Basis Of Presentation [Line Items]
Royalty payment obligation, percent									4.00%	4.00%
Third party maximum ownership, percent									10.00%	10.00%
Third party minimum ownership, percent									2.00%	2.00%
Expenses related to achievement of development milestone						$ 300
First Indication | Roche
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone				197,500
Collaborative arrangement, revenue based on development milestone | Roche
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone		$ 72,500
Collaborative arrangement, revenue based on development milestone | Roche | EBI-031
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone					$ 22,500
Phase II Study | Roche
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone		20,000
Collaborative arrangement, revenue based on regulatory milestone | Roche
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone		50,000
Collaborative arrangement, revenue based on commercialization milestone | Roche
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone		$ 75,000
Second Indication | Roche
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone				$ 65,000
Collaborative Arrangement, Revenue Based on Clinical Development Milestone | University of Zurich
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone									$ 500