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Collaboration and Licensing Agreements - Narrative (Details) $ in Thousands			1 Months Ended		3 Months Ended				6 Months Ended		13 Months Ended
	Oct. 01, 2021	Mar. 08, 2019	Mar. 31, 2020 item	Jan. 31, 2013 Program	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2020 item	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 agreement	Dec. 31, 2022 USD ($)	Mar. 31, 2022 USD ($)
Collaboration research and licensing agreements
Receivable					$ 20,019				$ 20,019			$ 28,997
Unrealized gain (loss) on equity securities					288		$ (6,545)		(2,610)	$ (9,974)
Number of technology license agreements \| agreement											2
Impairment on equity securities									0	138
Option and license agreement \| Alexion
Collaboration research and licensing agreements
Number of different target programs \| Program				1
Receivable					10,700				10,700
Deferred revenue					0				0
Option and license agreement \| Alexion \| Royalties
Collaboration research and licensing agreements
Revenue recognized					11,200		6,700		21,600	12,900
Research and License Agreement \| Astellas
Collaboration research and licensing agreements
Revenue recognized					0		0		0	5,000
Deferred revenue					0				0
Research and License Agreement \| Astellas \| Milestone
Collaboration research and licensing agreements
Contract asset													$ 5,000
Collaboration and License Agreement \| Genentech
Collaboration research and licensing agreements
Revenue recognized					0		0		0	0
Initial cost-sharing percentage		45.00%
Collaboration and License Agreement \| Genentech \| Research service
Collaboration research and licensing agreements
Deferred revenue					0				0
Collaboration and License Agreement \| Genentech \| XmAb24306
Collaboration research and licensing agreements
Receivable					1,000				1,000
Collaboration and License Agreement \| MorphoSys
Collaboration research and licensing agreements
Deferred revenue					0				0
Collaboration and License Agreement \| MorphoSys \| Royalties
Collaboration research and licensing agreements
Revenue recognized					2,000		1,200		3,900	3,500
Receivable					2,000				2,000
Collaboration and License Agreement \| Novartis
Collaboration research and licensing agreements
Revenue recognized					0		0		0	0
Deferred revenue					0				0
License Agreement \| INmune
Collaboration research and licensing agreements
Unrealized gain (loss) on equity securities					4,900		800		5,200	(2,600)
License Agreement \| Zenas
Collaboration research and licensing agreements
Revenue recognized					10,000		0		10,000	0
Deferred revenue					0				0
Impairment on equity securities					0		0		0	0
Second Collaboration And License Agreement \| Janssen
Collaboration research and licensing agreements
Revenue recognized					22,200		200		27,500	2,000
Receivable					2,200				2,200
Deferred revenue					7,900				7,900
Research license term	2 years
Proceeds from milestone payments						$ 5,000
Second Collaboration And License Agreement \| Janssen \| Maximum
Collaboration research and licensing agreements
Share development percentage	85.00%
Percentage of responsibility for development costs	20.00%
Second Collaboration And License Agreement \| Janssen \| Minimum
Collaboration research and licensing agreements
Share development percentage	80.00%
Percentage of responsibility for development costs	15.00%
Patent License Agreement \| Vir
Collaboration research and licensing agreements
Number of different target programs \| item			2					2
Receivable					100				100
Deferred revenue					0				0
Patent License Agreement \| Vir \| Royalties
Collaboration research and licensing agreements
Revenue recognized					100		22,100		1,500	92,300
Technology License Agreement \| Astria/Catabasis
Collaboration research and licensing agreements
Deferred revenue					0				0
Unrealized gain (loss) on equity securities					(3,500)		(2,400)		(3,900)	(1,500)
Technology License Agreement \| Viridian
Collaboration research and licensing agreements
Revenue recognized					0		0		0	0
Deferred revenue					0				0
Unrealized gain (loss) on equity securities					$ (1,200)		$ (5,000)		$ (3,900)	$ (5,900)