Collaboration and Licensing Agreements - Narrative (Details) ¥ in Billions	1 Months Ended					3 Months Ended			9 Months Ended		47 Months Ended	76 Months Ended
	Nov. 30, 2019 USD ($) item	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Nov. 30, 2017 USD ($)	Jun. 30, 2015 USD ($)	Sep. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2021 JPY (¥)	Dec. 31, 2020 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred revenue						$ 527,000			$ 527,000		$ 527,000	$ 527,000		$ 4,177,000
Revenue						1,173,000		$ 2,713,000	9,068,000	$ 5,762,000
Cost of revenue						0		0	1,000,000	141,000
Licensing revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue						2,000		0	5,007,000	706,000
Product supply revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue						285,000		1,357,000	411,000	1,400,000
2019 KKC Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue recognized									3,650,000
Deferred revenue						527,000			527,000		527,000	527,000		4,177,000
2019 KKC Agreement | KKC
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront license fees	$ 10,000,000
First installment of upfront license fees	$ 5,000,000
Term of payment of license fee, first installment	30 days
Second installment of upfront license fees	$ 5,000,000
Term of agreement	2 years
Revenue recognized						900,000		1,400,000	3,700,000	3,700,000
Deferred revenue						500,000			500,000		500,000	500,000		$ 4,200,000
2019 KKC Agreement | KKC | Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of separate collaborative agreements | item	1
2017 KKC Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Prepayment due							$ 2,900,000		2,947,000
2017 KKC Agreement | Licensing revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue						0	$ 5,000,000	0	5,000,000	0	10,000,000
2017 KKC Agreement | Product supply revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue						300,000			400,000
2017 KKC Agreement | Other revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue								1,400,000		1,400,000
2017 KKC Agreement | KKC
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront license fees				$ 30,000,000
Potential development milestones				$ 55,000,000
Potential commercialization milestones						76,100,000			76,100,000		$ 76,100,000	76,100,000	¥ 8.5
Fosun Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue						0			0
Fosun Agreement | Fosun Pharma
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payment received			$ 12,000,000
Potential development and commercialization milestones									$ 110,000,000
Threshold percentage of net sales for tiered royalties									20.00%
Knight Agreement | Knight
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payment received		$ 2,300,000
Potential development and commercialization milestones		$ 17,500,000
AstraZeneca Termination Agreement | AstraZeneca
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Percentage of royalty revenue					10.00%
Percentage of non-royalty revenue					20.00%
Maximum potential payment per agreement					$ 75,000,000
Cost of revenue						$ 0		$ 0	$ 1,000,000	$ 100,000		11,600,000
Payments made per agreement												$ 11,600,000