Stockholders' Equity - Additional Information (Details)			1 Months Ended				3 Months Ended	12 Months Ended		15 Months Ended	58 Months Ended
	Feb. 03, 2021 USD ($) Investor $ / shares shares	Jul. 14, 2020 USD ($)	Aug. 31, 2020 USD ($) $ / shares shares	Mar. 31, 2020 USD ($) shares	Nov. 30, 2019	Oct. 31, 2018 shares	Mar. 23, 2022 shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Mar. 23, 2022 shares	Dec. 31, 2021 USD ($) $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares authorized | shares								200,000,000	200,000,000		200,000,000
Common stock, par value | $ / shares								$ 0.0001	$ 0.0001		$ 0.0001
Preferred stock, shares authorized | shares								10,000,000			10,000,000
Preferred stock, par value | $ / shares								$ 0.0001			$ 0.0001
Common stock, shares outstanding | shares								29,455,668	24,753,102		29,455,668
Number of shares available for issuance | shares								6,549,848	4,195,805		6,549,848
Aggregate intrinsic value of stock options exercised								$ 400,000	$ 9,000
Proceeds from exercise of stock options								891,000	7,000
Fair value of stock options vested								$ 3,000,000.0	$ 4,100,000
Weighted-average grant-date fair value of options granted | $ / shares								$ 3.94	$ 3.11
Unrecognized compensation expense related to unvested stock options								$ 9,200,000			$ 9,200,000
Expected recognition period of unrecognized compensation expense								2 years 7 months 6 days
Dividends paid								$ 0
Equity Unit Purchase Agreements
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Gross proceeds from issuance of common stock	$ 30,000,000.0
Proceeds from issuance of common stock	$ 29,900,000
Number of institutional investors | Investor	2
Shares upon exercise of warrants | shares	1,285,713
Follow-on Offering
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Proceeds from issuance of common stock									$ 35,717,000
Open Market Sales Agreement | 2019 ATM Facility
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Commission rate					3.00%
Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock, Shares | shares									83,662
Common Stock | Equity Unit Purchase Agreements
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock, Shares | shares	4,285,710
Common Stock | Follow-on Offering
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock, Shares | shares			5,461,169
Sale of stock, price per share | $ / shares			$ 7.00
Gross proceeds from issuance of common stock			$ 38,200,000
Proceeds from issuance of common stock			$ 35,700,000
Common Stock | Over Allotment Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock, Shares | shares			461,169
Common Stock | Open Market Sales Agreement | 2019 ATM Facility
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock, Shares | shares									925,489
Gross proceeds from issuance of common stock									$ 8,400,000
Proceeds from issuance of common stock									8,100,000
Common stock shares maximum aggregate offering price								$ 8,450,000
Stock issuance costs									$ 300,000
Common Stock | Open Market Sales Agreement | 2020 ATM Facility
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock, Shares | shares								788,685
Gross proceeds from issuance of common stock								$ 10,400,000
Proceeds from issuance of common stock								10,000,000.0
Common stock shares maximum aggregate offering price		$ 150,000,000
Stock issuance costs								$ 400,000
Common Stock | Purchase Agreement | Lincoln Park Capital Fund, LLC
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock, Shares | shares				65,374
Stock issuance costs				$ 400,000
Estimated maximum amount of common stock issuable				$ 15,000,000.0
Term of purchase agreement				36 months
Fair market value of commitment shares				$ 200,000
Common Stock | Subsequent Event | Open Market Sales Agreement | 2020 ATM Facility
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock, Shares | shares							0
Common Stock | Subsequent Event | Purchase Agreement | Lincoln Park Capital Fund, LLC
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock, Shares | shares										0
Common Stock Warrants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for issuance | shares								1,366,141	80,428		1,366,141
Common Stock Warrants | Equity Unit Purchase Agreements
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Sale of stock, price per share | $ / shares	$ 25.00
Gross proceeds from issuance of common stock	$ 25,000,000
Warrants exercisable, per share exercise price | $ / shares	$ 14.00
2018 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity incentive plan description								The number of shares of common stock reserved for issuance under the 2018 Plan will automatically increase on January 1 of each calendar year through January 1, 2028, in an amount equal to 5.0% of the total number of shares of the Company’s capital stock outstanding on the last day of the calendar month before the date of each automatic increase, or a lesser number of shares determined by the Board.
2018 Equity Incentive Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for issuance | shares								467,024			467,024
2018 Equity Incentive Plan | Common Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Minimum options exercise price as percentage of fair market value of common stock								100.00%
Remaining vesting period								3 years
2018 Equity Incentive Plan | Common Stock Options | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award expiration period								10 years
2018 Equity Incentive Plan | Tranche One | Common Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage								25.00%
2017 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested shares issued under early exercise which are subject to repurchase | shares								43,135	153,690		43,135
Unvested stock liability								$ 53,000	$ 125,000		$ 53,000
2017 Equity Incentive Plan | Short Term Portion Of Unvested Stock Liability
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested stock liability									72,000
2017 Equity Incentive Plan | Long Term Portion Of Unvested Stock Liability
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested stock liability									$ 53,000
2018 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized for issuance under purchase rights granted to employees | shares						343,275
Employee stock purchase plan description								Equity Stock Purchase Plan (ESPP) whereby eligible employees may elect to withhold up to 15% of their earnings to purchase shares of the Company’s common stock at a price per share equal to the lower of (i) 85% of the fair market value of a share of the Company’s common stock on the first date of an offering or (ii) 85% of the fair market value of a share of the Company’s common stock on the date of the purchase right (purchase right). Initially, 343,275 shares of the Company’s common stock were approved for issuance under the ESPP pursuant to purchase rights granted to the Company’s employees or to employees of any of the Company’s designated affiliates. The number of shares of the Company’s common stock reserved for issuance will automatically increase on January 1 of each calendar year through January 1, 2028, by the lesser of (1) 1.0% of the total number of shares of the Company’s common stock outstanding on the last day of the calendar month before the date of the automatic increase, and (2) 343,275 shares; provided that before the date of any such increase, the Board may determine that such increase will be less than the amount set forth in clauses (1) and (2)
Withhold Percentage of employees earnings to purchase shares of common stock						15.00%
Number of shares issued | shares								90,402			169,166
Number of shares available for future issuance under employee stock purchase plan | shares								769,658
2018 Employee Stock Purchase Plan | IPO
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Minimum stock price per share as percentage of fair market value of common stock						85.00%
2018 Employee Stock Purchase Plan | Purchase Right
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Minimum stock price per share as percentage of fair market value of common stock						85.00%