Collaboration and Licensing Agreements - Narrative (Details)		1 Months Ended										3 Months Ended			12 Months Ended
	Oct. 01, 2021 USD ($) candidate agreement d $ / shares shares	Dec. 31, 2021 USD ($) candidate	Nov. 30, 2021 USD ($)	Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)	Nov. 30, 2020 USD ($) candidate	Aug. 31, 2020 item	Apr. 30, 2020 USD ($)	Jan. 31, 2020 compound	Jun. 30, 2016 target	Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2020 option	Dec. 31, 2022 USD ($) program	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($) target	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Nov. 30, 2022 USD ($)	Mar. 31, 2020 USD ($)	Feb. 28, 2019 USD ($)
Collaboration research and licensing agreements
Receivable		$ 66,384,000													$ 28,997,000	$ 66,384,000
Unrealized gain (losses) recognized on equity securities															23,434,000	20,988,000	$ 105,000
Realized gain on investment															0	18,301,000
Net gains recognized on equity securities															23,434,000	39,289,000	105,000
Proceeds from sale of common stock																28,920,000
Zenas
Collaboration research and licensing agreements
Increase in estimated fair value of equity securities																				$ 17,900,000
Zenas | Warrant
Collaboration research and licensing agreements
Equity shares estimated fair value																				34,500,000
Zenas | Convertible Debt Securities
Collaboration research and licensing agreements
Equity shares estimated fair value																				$ 7,700,000
License, Development, and Commercialization Agreement | Aimmune
Collaboration research and licensing agreements
Revenue recognized															0	0
Deferred revenue		0													0	0
Option and license agreement | Alexion
Collaboration research and licensing agreements
Revenue recognized															29,400,000	22,200,000	26,200,000
Deferred revenue															0
Receivable															14,800,000
Option and license agreement | Alexion | Royalties
Collaboration research and licensing agreements
Revenue recognized															29,400,000	22,200,000	16,200,000
Option and license agreement | Alexion | Milestone
Collaboration research and licensing agreements
Revenue recognized																	10,000,000
Research and License Agreement | Amgen, Inc.
Collaboration research and licensing agreements
Revenue recognized															0	0	0
Deferred revenue															$ 0
Research and License Agreement | Amgen, Inc. | Discovery Program
Collaboration research and licensing agreements
Number of discovery programs in clinical development | program															1
Research and License Agreement | Astellas
Collaboration research and licensing agreements
Revenue recognized															$ 5,000,000		2,500,000
Deferred revenue															0
Proceeds from milestone payments															5,000,000
Research and License Agreement | Novartis | Milestone
Collaboration research and licensing agreements
Revenue recognized																3,000,000
Collaboration and License Agreement | Genentech
Collaboration research and licensing agreements
Revenue recognized															0	2,500,000	3,500,000
Transaction price																						$ 120,000,000
Cost sharing receivable (payable)															200,000
Collaboration and License Agreement | Genentech | XmAb306
Collaboration research and licensing agreements
Standalone selling price																						111,700,000
Collaboration and License Agreement | Genentech | XmAb435
Collaboration research and licensing agreements
Standalone selling price																					$ 4,100,000
Collaboration and License Agreement | Genentech | Research service
Collaboration research and licensing agreements
Deferred revenue															0
Transaction price															8,300,000
Standalone selling price																						$ 4,200,000
Collaboration and License Agreement | Janssen
Collaboration research and licensing agreements
Revenue recognized		5,000,000													0		0
Deferred revenue															30,300,000
Transaction price							$ 50,000,000
Percentage of funding for development costs							20.00%
Percentage of co-detailing activities							30.00%
Research license term	2 years
Number of collaboration and license agreements | agreement	2
Collaboration and License Agreement | Janssen | Research collaboration
Collaboration research and licensing agreements
Revenue recognized																50,000,000
Collaboration and License Agreement | MorphoSys
Collaboration research and licensing agreements
Revenue recognized																	39,000,000
Deferred revenue															0
Collaboration and License Agreement | MorphoSys | Royalties
Collaboration research and licensing agreements
Revenue recognized															7,800,000	5,900,000
Contract asset															2,200,000
Collaboration and License Agreement | MorphoSys | Milestone
Collaboration research and licensing agreements
Revenue recognized																12,500,000
Collaboration and License Agreement | Novartis
Collaboration research and licensing agreements
Revenue recognized															0	43,100,000	0
Deferred revenue															0
Receivable															$ 30,000.00
Collaboration and License Agreement | Novartis | Global Discovery Program
Collaboration research and licensing agreements
Revenue recognized																40,100,000			$ 40,100,000
Number of programs delivered | program															2
Collaboration and License Agreement | Novartis | FC Licenses | Maximum
Collaboration research and licensing agreements
Number of targets against which non-exclusive license is provided | target											10
Collaboration and License Agreements | Janssen
Collaboration research and licensing agreements
Revenue recognized															$ 7,000,000	113,800,000
License Agreement | INmune
Collaboration research and licensing agreements
Unrealized gain (losses) recognized on equity securities															(7,300,000)	15,100,000
Consideration on sale of option					$ 18,300,000
Cash consideration on sale of option					15,000,000
Realized gain on investment					18,300,000											18,300,000
License Agreement | INmune | Common Stock
Collaboration research and licensing agreements
Unrealized gain (losses) recognized on equity securities												$ 2,000,000
Cash consideration on sale of option					15,000,000
Purchase amount of share options or equity in noncash transaction				$ 800,000
Gain on fair value of option												1,100,000
Net gains recognized on equity securities				$ 900,000
License Agreement | INmune | Other Income
Collaboration research and licensing agreements
Unrealized gain (losses) recognized on equity securities													$ 27,800,000
License Agreement | INmune | Other Income | Common Stock
Collaboration research and licensing agreements
Net gains recognized on equity securities												$ 900,000
License Agreement | Zenas
Collaboration research and licensing agreements
Revenue recognized															0	14,900,000	16,100,000
Deferred revenue															$ 0
Transaction price			$ 14,900,000				$ 16,100,000
Purchase amount of share options or equity in noncash transaction							$ 16,100,000
Number of drug candidates | candidate							3
Number of collaboration and license agreements | program															2
Percentage of equity of private company			15.00%				15.00%
Milestones or royalties in transaction price			$ 0				$ 0
Patent License Agreement | Vir
Collaboration research and licensing agreements
Revenue recognized															$ 115,400,000	52,700,000	$ 300,000
Deferred revenue															0
Receivable															4,800,000
Potential milestone payment																		$ 154,000,000
Number of different target programs | target																	2
Upfront and milestone payment received																		2,000,000
Contract asset					$ 500,000								$ 500,000
Patent License Agreement | Vir | Royalties
Collaboration research and licensing agreements
Revenue recognized															114,900,000	52,200,000
Second Collaboration And License Agreement | Janssen
Collaboration research and licensing agreements
Transaction price	$ 96,100,000
Research license term	2 years
Nonrefundable upfront payment	$ 100,000,000
Potential milestone payment	1,187,500,000
Proceeds from sale of common stock	$ 28,900,000
Share development percentage	80.00%
Percentage of responsibility for development costs	20.00%
Number of candidates for which option to advance for development and commercialization | candidate	4
Number of drug candidates | candidate	4
Discount on proceeds from sale	$ 3,900,000
Second Collaboration And License Agreement | Janssen | Research service
Collaboration research and licensing agreements
Revenue recognized															7,000,000	300,000
Standalone selling price	37,600,000
Performance obligation	37,600,000		37,600,000
Second Collaboration And License Agreement | Janssen | Licensing
Collaboration research and licensing agreements
Revenue recognized	58,500,000		58,500,000
Standalone selling price	58,500,000
Second Collaboration And License Agreement | Johnson & Johnson Innovation, JJDC, Inc. | Common Stock
Collaboration research and licensing agreements
Proceeds from sale of common stock	$ 25,000,000
Number of trading days | d	30
Weighted average price (in dollars per share) | $ / shares	$ 33.4197
Total equity shares (in shares) | shares	748,062
Second Collaboration And License Agreement | Zenas
Collaboration research and licensing agreements
Potential milestone payment			470,000,000
Warrants			$ 14,900,000
Licensing Agreements | INmune
Collaboration research and licensing agreements
Revenue recognized															0	0	$ 0
Technology License Agreement | Astria/Catabasis
Collaboration research and licensing agreements
Deferred revenue															0
Impairment charge															100,000
Unrealized gain (losses) recognized on equity securities															6,100,000	4,500,000
Technology License Agreement | Gilead
Collaboration research and licensing agreements
Revenue recognized									$ 7,500,000						0	0	13,500,000
Deferred revenue															0
Number of additional antibody compounds | compound										3
Number of options exercised | option														3
Technology License Agreement | Viridian
Collaboration research and licensing agreements
Revenue recognized															0	7,500,000	6,000,000
Deferred revenue															0
Purchase amount of share options or equity in noncash transaction		$ 7,500,000				$ 6,000,000
Research license term		1 year
Number of antibodies | candidate		3
Technology License Agreement | Viridian | Maximum
Collaboration research and licensing agreements
Potential milestone payment		$ 24,800,000														24,800,000
Technology License Agreement | Viridian | Xtend Fc Technology
Collaboration research and licensing agreements
Transaction price						$ 6,000,000											6,000,000
Technology License Agreement | Viridian | Antibody Libraries
Collaboration research and licensing agreements
Transaction price		7,500,000														7,500,000
Technology License Agreement | Omeros
Collaboration research and licensing agreements
Revenue recognized															0	0	$ 5,000,000
Deferred revenue															$ 0
Number of additional antibodies | item								3
Development-based | Patent License Agreement | Vir
Collaboration research and licensing agreements
Potential milestone payment																		4,000,000
Development-based | Second Collaboration And License Agreement | Janssen
Collaboration research and licensing agreements
Potential milestone payment	$ 289,400,000
Development-based | Technology License Agreement | Viridian
Collaboration research and licensing agreements
Potential milestone payment		1,800,000														1,800,000
Regulatory-based | Patent License Agreement | Vir
Collaboration research and licensing agreements
Potential milestone payment																		30,000,000
Regulatory-based | Second Collaboration And License Agreement | Janssen
Collaboration research and licensing agreements
Potential milestone payment	378,100,000
Regulatory-based | Technology License Agreement | Viridian
Collaboration research and licensing agreements
Potential milestone payment		3,000,000														3,000,000
Sales-based | Patent License Agreement | Vir
Collaboration research and licensing agreements
Potential milestone payment																		$ 120,000,000
Sales-based | Second Collaboration And License Agreement | Janssen
Collaboration research and licensing agreements
Potential milestone payment	$ 520,000,000
Sales-based | Technology License Agreement | Viridian
Collaboration research and licensing agreements
Potential milestone payment		$ 20,000,000														$ 20,000,000