Collaboration and Licensing Agreements - Narrative (Details) ¥ in Billions	1 Months Ended					3 Months Ended			6 Months Ended		44 Months Ended	73 Months Ended
	Nov. 30, 2019 USD ($) item	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Nov. 30, 2017 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2021 JPY (¥)	Dec. 31, 2020 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred revenue						$ 1,412,000			$ 1,412,000		$ 1,412,000	$ 1,412,000		$ 4,177,000
Revenue						1,313,000		$ 1,836,000	7,895,000	$ 3,049,000
Cost of revenue						0		141,000	1,000,000	141,000
Licensing revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue						3,000		706,000	5,005,000	706,000
Product supply revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue						0		5,000	126,000	43,000
2019 KKC Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue recognized									2,765,000
Deferred revenue						1,412,000			1,412,000		1,412,000	1,412,000		4,177,000
2019 KKC Agreement | KKC
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront license fees	$ 10,000,000.0
First installment of upfront license fees	$ 5,000,000.0
Term of payment of license fee, first installment	30 days
Second installment of upfront license fees	$ 5,000,000.0
Term of agreement	2 years
Revenue recognized						1,300,000		1,100,000	2,800,000	2,300,000
Deferred revenue						1,400,000			1,400,000		1,400,000	1,400,000		$ 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	0	5,000,000.0	0	10,000,000.0
2017 KKC Agreement | Product supply revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue						0			100,000
2017 KKC Agreement | Other revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue								5,000.0		43,000.0
2017 KKC Agreement | KKC
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront license fees				$ 30,000,000.0
Potential development milestones				$ 55,000,000.0
Potential commercialization milestones						76,500,000			76,500,000		$ 76,500,000	76,500,000	¥ 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			$ 12,000,000.0
Potential development and commercialization milestones									$ 110,000,000.0
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		$ 17,900,000
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					$ 75,000,000.0
Cost of revenue						$ 0		$ 100,000	$ 1,000,000.0	$ 100,000		11,600,000
Payments made per agreement												$ 10,600,000