Stock-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Number of Shares
Outstanding, beginning balance (in shares)	1,297,029
Granted, (in shares)	864,616
Exercised (in shares)	(17,689)
Forfeited (in shares)	(269,442)
Outstanding, ending balance (in shares)	1,874,514	1,297,029
Exercisable, ending balance (in shares)	682,632
Vested and expected to vest, ending balance (in shares)	1,404,246
Weighted Average Exercise Price
Outstanding, beginning balance (in dollars per share)	$ 17.05
Granted (in dollars per share)	8.06
Exercised (in dollars per share)	7.25
Forfeited (in dollars per share)	17.43
Outstanding, ending balance (in dollars per share)	12.94	$ 17.05
Exercisable (in dollars per share)	17.42
Vested and expected to vest (in dollars per share)	$ 13.35
Weighted Average Contractual Term (Years)
Outstanding	8 years 3 months 18 days	8 years 4 months 24 days
Exercisable	7 years
Vested and expected to vest	8 years 1 month 6 days
Aggregate Intrinsic Value
Outstanding beginning balance	$ 1,286
Outstanding ending balance	7	$ 1,286
Exercisable	0
Vested and expected to vest	$ 4

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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- Definition

The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.