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Common Stock - Stock Options - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares reserved for options currently outstanding	522,090	227,442
Number of shares granted	294,650
Weighted average fair value of stock options granted	$ 9.96
Unrecognized compensation expense related to stock options granted	$ 3,400,000	$ 2,200,000
Aggregate intrinsic value of options exercised	0	$ 0	$ 0
Aggregate intrinsic value of the outstanding options	19,500
Aggregate intrinsic value of the exercisable outstanding options	$ 0
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average period, restricted stock awards	2 years 6 months 21 days	2 years 6 months 21 days
Restricted Stock Unit [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted shares reserved for issuance under incentive plan	53,250
Award vesting period	4 years
Weighted-average period, restricted stock awards	1 year 5 months 26 days
2018 Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares reserved for issuance under incentive plan	4,145
Award expiration period	10 years
2018 Equity Incentive Plan [Member] \| Minimum [Member] \| Employees and Consultants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period	3 years
2018 Equity Incentive Plan [Member] \| Minimum [Member] \| Board of Directors [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period	1 year
2018 Equity Incentive Plan [Member] \| Maximum [Member] \| Employees and Consultants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period	4 years
2018 Equity Incentive Plan [Member] \| Maximum [Member] \| Board of Directors [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period	3 years
2018 Equity Incentive Plan [Member] \| Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares reserved for issuance under incentive plan	521,100
Common shares reserved for options currently outstanding	463,705
New Employee Inducement Grants [Member] \| Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares reserved for options currently outstanding	45,000
Award expiration period	10 years
Number of shares granted	45,000
2017 Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award expiration period	10 years
2017 Equity Incentive Plan [Member] \| Minimum [Member] \| Employees and Consultants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period	3 years
2017 Equity Incentive Plan [Member] \| Minimum [Member] \| Board of Directors [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period	1 year
2017 Equity Incentive Plan [Member] \| Maximum [Member] \| Employees and Consultants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period	4 years
2017 Equity Incentive Plan [Member] \| Maximum [Member] \| Board of Directors [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period	3 years
2017 Equity Incentive Plan [Member] \| Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares reserved for issuance under incentive plan	13,156
2010 Performance Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award expiration period	10 years
2010 Performance Incentive Plan [Member] \| Minimum [Member] \| Employees and Consultants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period	3 years
2010 Performance Incentive Plan [Member] \| Minimum [Member] \| Board of Directors [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period	1 year
2010 Performance Incentive Plan [Member] \| Maximum [Member] \| Employees and Consultants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period	4 years
2010 Performance Incentive Plan [Member] \| Maximum [Member] \| Board of Directors [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period	3 years
2010 Performance Incentive Plan [Member] \| Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares reserved for issuance under incentive plan	229