Collaboration and Licensing Agreements - Additional Information (Details)	1 Months Ended					3 Months Ended		6 Months Ended		12 Months Ended	32 Months Ended
	Nov. 30, 2019 USD ($) item	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Nov. 30, 2017 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2017 USD ($)	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue						$ 1,836,000	$ 18,000	$ 3,049,000	$ 18,000
Unbilled revenue						750,000		750,000			$ 750,000	$ 750,000
Cost of revenue						141,000		141,000
Other
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue						5,000	18,000	43,000	18,000
Astra Zeneca
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Cost of revenue								100,000	0
Cost of revenue, aggregate amount recognized						10,600,000		10,600,000			10,600,000
Cost of revenue, Amount Paid								10,600,000
Astra Zeneca | Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Payment per termination agreement					$ 75,000,000.0			75,000,000.0
2019 KKC Agreement | Kyowa Kirin Co. Ltd
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of pre-clinical study-ready compounds | item	2
Number of compounds inhibiting the first undisclosed target | item	1
Upfront payment recognized	$ 10,000,000.0
License fee receivable, first installment	$ 5,000,000.0
Term of payment of license fee, first installment	30 days
License fee receivable, Second instalment	$ 5,000,000.0
Term of agreement	2 years
Initial transaction price	$ 10,000,000.0
Revenue						1,100,000		2,300,000
Change in estimates								0
Transaction price allocated to partially unsatisfied performance obligations						7,200,000		7,200,000			7,200,000
Uncharged license fees						2,200,000		2,200,000			2,200,000
2019 KKC Agreement | Kyowa Kirin Co. Ltd | Minimum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of development candidates | item	1
Number of separate collaborative agreements | item	1
2017 KKC Agreement | Kyowa Kirin Co. Ltd
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment recognized				$ 30,000,000.0
Uncharged license fees												1,000,000.0
Upfront payment received				30,000,000.0
Unbilled revenue												$ 5,000,000.0
Development milestones Received											$ 5,000,000.0
Commercialization milestones				78,900,000
2017 KKC Agreement | Kyowa Kirin Co. Ltd | Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development milestones				$ 55,000,000.0
2017 KKC Agreement | Kyowa Kirin Co. Ltd | Other
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue						5,000		43,000	18,000
XuanZhu Agreement | XuanZhu
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue								0
Upfront payment received	$ 750,000
License fee recognized	1,500,000
Second milestone payment	$ 750,000
Fosun Agreement | Fosun Pharma
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment recognized			$ 12,000,000.0							$ 12,000,000.0
Revenue						0	0	0	0
Future development milestones										$ 110,000,000.0
Fosun Agreement | Fosun Pharma | Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Threshold percentage of net sales for tiered royalties			20.00%
Knight Agreement | Knight
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue						$ 700,000	$ 0	$ 700,000	$ 0
Total payments, including an up-front payment and development and sales milestones to be received		$ 18,300,000
Development and Commercialization | Astra Zeneca
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of royalty revenue (as a percent)					10.00%
Percentage of non royalty revenue (as a percent)					20.00%