Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2019
Significant Accounting Policies [Line Items]
Restricted cash deposit	$ 327,000	$ 327,000
Restricted cash noncurrent	327,000	327,000	$ 327,000
Income tax expense (benefit)	0	0
Other income	1,000	515,000	$ 270,000
Operating lease, right-of-use asset	3,579,000	$ 4,988,000		$ 4,600,000
Operating lease liability	$ 4,418,000			$ 5,900,000
ASC Topic 606 [Member]
Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2017
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, immaterial effect	true
ASU 2016-02 [Member]
Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2019
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, immaterial effect	true
ASU 2018-13 [Member]
Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2020
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, immaterial effect	true
Laboratory Equipment [Member]
Significant Accounting Policies [Line Items]
Useful life of asset	5 years
Computer Equipment [Member]
Significant Accounting Policies [Line Items]
Useful life of asset	3 years
Computer Software [Member]
Significant Accounting Policies [Line Items]
Useful life of asset	2 years
Furniture and Office Equipment [Member]
Significant Accounting Policies [Line Items]
Useful life of asset	5 years
Leasehold Improvements [Member]
Significant Accounting Policies [Line Items]
Useful life of asset	shorter of the lease term or the estimated useful life of the related asset