Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands				1 Months Ended				8 Months Ended	12 Months Ended
	Feb. 08, 2022	Jan. 21, 2020	Jul. 15, 2015	Jan. 31, 2022	Feb. 28, 2021	Jun. 30, 2020	May 31, 2020	Feb. 28, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock shares reserved for issuance									17,205,249	16,386,314
Total stock-based compensation									$ 12,890	$ 9,470	$ 5,695
Total unrecognized stock-based compensation related to unvested stock options									$ 25,300
Weighted-average period									2 years 8 months 12 days
Performance Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding and unvested									1,029,000	1,104,500
Total stock-based compensation									$ 3,000	$ 900
Total unrecognized stock-based compensation related to unvested stock options									$ 5,300
Subsequent Event [Member] | Performance Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options vested				257,255
2018 Equity Inducement Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock shares reserved for issuance									1,037,500			37,500
Common shares authorized to be issued during the period					500,000	500,000		1,000,000
Stock option life in years									10 years
2018 Equity Inducement Plan [Member] | Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares authorized to be issued during the period	500,000
2015 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock shares reserved for issuance									5,123,736
Common shares authorized to be issued during the period		4,312,500
Stock option life in years									10 years
Percentage threshold of outstanding shares increased annually under the plan									4.00%
Employee stock purchase plan description									the number of shares equal to 4% of the total outstanding shares of the Company’s common stock as of the immediately preceding December 31.
2008 Plan, 2015 Plan and 2018 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares authorized to be issued during the period									945,139
Weighted-average grant date fair values of options granted									$ 12.54	$ 8.81	$ 50.40
Options, exercises in period									64,847	0
Aggregate intrinsic value of options exercised									$ 500		$ 100
Total grant date fair value of options vested									$ 11,300	$ 5,200	$ 6,000
2008 Plan, 2015 Plan and 2018 Plan [Member] | Share Based Compensation Arrangement Modification [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrant expiration period after specified event							75 days
Compensation costs relating to vesting acceleration and modification										$ 2,200
Option expiration date							Apr. 10, 2022
2015 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock shares reserved for issuance			17,500						17,500	17,500
Common shares authorized to be issued during the period			85,000
Employee stock purchase plan description									The aggregate number of shares issued over the term of the 2015 Employee Stock Purchase Plan will not exceed 85,000 shares of common stock. The ESPP will not become effective until such time as the Compensation Committee determines in the future, and as of December 31, 2021, the initial offering periods had not commenced.
Number of common stock issued									0