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Stockholders' Equity - Additional Information (Details) - USD ($)					1 Months Ended	3 Months Ended	9 Months Ended
	Aug. 06, 2021	Jul. 02, 2021	Jun. 16, 2020	Apr. 01, 2019	Jun. 30, 2020	Jun. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Jan. 31, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares authorized			400,000,000				400,000,000		400,000,000
Preferred stock undesignated shares authorized			40,000,000				40,000,000		40,000,000
Common stock par value per share			$ 0.0001				$ 0.0001		$ 0.0001
Preferred stock par value per share			$ 0.0001				$ 0.0001		$ 0.0001
Sale of common stock maximum aggregate offering price		$ 150,000,000.0
Termination notice period for sales agreement		10 days
Proceeds from issuance of common stock		$ 0
Reclassified accumulated deficit from predecessor deficit to additional paid in capital				$ 44,100,000
Award vesting period							4 years
Weighted-average grant date fair value of options granted							$ 16.83	$ 10.22
Time-based Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost							$ 48,300,000
Weighted-average period of unrecognized compensation cost							2 years 10 months 24 days
2013 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Units initially reserved for issuance											2,127,013
Increased to number of shares reserved under plan										4,771,615
2013 Equity Incentive Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expiration period							10 years
2020 Incentive Award Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares of common stock initially reserved for issuance					3,900,000	3,900,000
Percentage of shares of common stock outstanding on final day of immediately preceding calendar year					5.00%	5.00%
Number of remaining shares available for issuance							2,755,467
2020 Incentive Award Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expiration period							10 years
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Participant maximum contribution as percentage of eligible compensation					15.00%	15.00%
Percentage of purchase price of shares of lower of fair market value					85.00%
Shares of common stock available for issuance							657,475
Shares issued under ESPP							14,235	0
Unrecognized compensation cost							$ 100,000
Weighted-average period of unrecognized compensation cost							2 months 12 days
Employee Stock Purchase Plan \| Accounts Payable and Accrued Liabilities
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding liability							$ 300,000
Series A Convertible Preferred Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Preferred unit converted into convertible preferred stock				1
Series B Convertible Preferred Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Preferred unit converted into convertible preferred stock				1
Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common unit converted into common stock				1
Convertible preferred stock converted into shares of common stock						17,921,000
IPO
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Sale of stock number of shares issued in transaction			16,560,000
Sale of stock, price per share			$ 18.00
Proceeds from the IPO, net of underwriting discounts, commissions and offering costs			$ 274,100,000
Convertible preferred stock converted into shares of common stock			17,921,069
IPO \| Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares authorized			400,000,000
Convertible preferred stock converted into shares of common stock					17,921,069
Follow-on Public Offering \| Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Sale of stock number of shares issued in transaction	9,200,000
Sale of stock, price per share	$ 18.00
Proceeds from the follow-on public offering, net of underwriting discounts, commissions and offering costs	$ 155,100,000