Collaboration, Development and License Agreements - Serum License Agreement (Details) - USD ($)	1 Months Ended			12 Months Ended
	Mar. 31, 2021	Sep. 30, 2019	Jul. 31, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Issuance of common stock				$ 29,011,000
Revenue from Contract with Customer, Excluding Assessed Tax				1,535,000	$ 1,000,000
Deferred revenue, noncurrent				913,000	854,000
Capitalized contract cost, Current				1,967,000	1,973,000
Capitalized contract cost, Noncurrent				96,000	90,000
Deferred revenue				20,838,000	18,748,000
License revenue
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Contractual liability				18,600,000	18,700,000
Capitalized contract costs					2,100,000	$ 2,100,000
Revenue				0	0
Deferred revenue, noncurrent				913,000	854,000
Capitalized contract cost, Current				2,000,000.0	2,000,000.0
Capitalized contract cost, Noncurrent				96,000	90,000
Licenses and know-how
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Contractual liability				14,500,000
Development support services
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Contractual liability				79,000
Research and Development Option
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Contractual liability				892,000
Manufacturing rights option
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Contractual liability				4,100,000
License Agreement with SIBV
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Upfront payment received			$ 5,000,000
CFF
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Revenue from Contract with Customer, Excluding Assessed Tax					$ 1,000,000.0
Deferred revenue				476,000
License Agreement with SAMR
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Buy back manufacturing rights		$ 5,000,000
Upfront payment received		15,000,000	$ 5,000,000
Maximum additional payments entitled		$ 42,500,000		42,500,000
License Agreement and Option Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Fair value of net proceeds						5,000,000.0
Fair value of gross proceeds						5,400,000
Contractual liability				19,600,000		19,600,000
Deferred revenue based on upfront payments				15,000,000.0		15,000,000.0
Deferred revenue from equity allocation				4,600,000		4,600,000
Issuance costs from equity allocation						$ 441,000
Kermode Licensing and Product Discovery Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Maximum additional payments entitled				250,000
Gross Transaction Price				750,000
Revenue recognized				465,000
Deferred revenue				285,000
Kermode Licensing and Product Discovery Agreement | Upfront payment
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Maximum additional payments entitled				250,000
Kermode Licensing and Product Discovery Agreement | License revenue | Upfront payment
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Upfront payment received	$ 500,000
Kermode Licensing and Product Discovery Agreement | Research and Development Option
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Maximum additional payments entitled				250,000
Serum International B.V. ("SIBV")
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Issuance of common stock (in shares)			801,820
Issuance of common stock			$ 10,000,000
Serum International B.V. ("SIBV") | License Agreement with SIBV
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Deferred revenue from equity allocation				$ 4,600,000
Restricted common stock | Serum International B.V. ("SIBV")
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Issuance of common stock (in shares)			801,820
Issuance of common stock			$ 10,000,000