Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	1 Months Ended		3 Months Ended	9 Months Ended
	Jan. 31, 2018	Oct. 31, 2017	Sep. 30, 2020	Sep. 30, 2020
Summary Of Significant Accounting Policies [Line Items]
Increase in expected cost percentage			2.30%
Reduced revenue			$ 1,700,000
Available-for-Sale Investments | ASU 2016-13
Summary Of Significant Accounting Policies [Line Items]
Accrued interest receivable			1,200,000	$ 1,200,000
AbbVie Biotechnology Limited
Summary Of Significant Accounting Policies [Line Items]
Upfront payments		$ 205,000,000
Upfront payment received	$ 200,000,000	5,000,000
Exclusive option rights exercised for each program		250,000,000
Collaboration revenue			5,900,000	16,200,000
Deferred revenue			$ 137,200,000	137,200,000
AbbVie Biotechnology Limited | Maximum
Summary Of Significant Accounting Policies [Line Items]
Additional milestone payments per program related to initiation of certain clinical studies and regulatory approval		$ 242,800,000
Innovent
Summary Of Significant Accounting Policies [Line Items]
Collaboration revenue				0
Development milestone				11,500,000
Sales milestone				112,500,000
Money Market Funds
Summary Of Significant Accounting Policies [Line Items]
Unrealized gains or loss on money market funds				$ 0