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Share-based compensation arrangement by share-based payment award offering period.

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Share-based compensation arrangement by share-based payment award purchase period.

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Share-based compensation arrangement by share-based payment award, shares subject to repurchase.

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Share based compensation by share based payment award common stock granted in period, term.

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Share-based payment arrangement, withheld on behalf of employees for future purchase.

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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Amount of cost to be recognized for option under share-based payment arrangement.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Description of service or performance condition required to be met for earning right to award under share-based payment arrangement. Includes, but is not limited to, combination of market, performance or service condition.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Number of shares authorized for issuance under share-based payment arrangement.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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Gross number of share options (or share units) granted during the period.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Maximum number of shares that may be issued in accordance with the plan as a proportion of outstanding capital stock.

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Percentage of vesting of award under share-based payment arrangement.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Purchase price of common stock expressed as a percentage of its fair value.

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Number of shares issued during the period as a result of an employee stock purchase plan.

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Stock-based Compensation - Additional Information (Details) - USD ($)	1 Months Ended	2 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Jul. 31, 2021	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2018	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance			34,830,360		34,830,360			29,685,655
Share-based compensation, shares subject to repurchase			1,282,031		1,282,031			1,854,427
Stock-based compensation			$ 5,232,000	$ 3,017,000	$ 14,729,000	$ 5,448,000
Share-based compensation, vesting rights description					The restricted stock vests 25% one year from the vesting commencement date and monthly thereafter over a three-year period and is subject to repurchase by the Company in the event of any voluntary or involuntary termination of services to the Company prior to vesting.
Accrued Expenses and Other Current Liabilities
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, liabilities associated with shares issued with repurchase rights			$ 1,900,000		$ 1,900,000			$ 2,900,000
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, common stock grant in period, term					5 years
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance			17,642,185		17,642,185			13,818,212
Stock vesting period					4 years
Weighted-average grant date fair value of options granted			$ 4.91	$ 12.29	$ 7.50	$ 3.96
Unrecognized compensation cost related to unvested stock option grants			$ 57,000,000.0		$ 57,000,000.0
Unrecognized compensation cost expected to be recognized as expense, period					2 years 7 months 2 days
Intrinsic value of options exercised			$ 1,500,000	$ 663,000	$ 5,900,000	$ 2,500,000
Share-based compensation, options granted that vest based on performance milestone					5,732,046
Stock Options \| Minimum \| At the Time Option is Granted
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of fair market value of common stock					100.00%
Stock Options \| Minimum \| For Holders of More Than 10% of Company's Total Combined Voting Power of All Classes of Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of fair market value of common stock					110.00%
Stock Options \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, plan expiration period					10 years
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock vesting period							3 years
Restricted stock granted			0	0	0	0	1,795,827
Weighted-average grant date fair value of restricted stock granted							$ 0
Share-based Compensation, common stock shares subject to forfeiture			212,941		212,941			212,941
Total unrecognized compensation related to unvested restricted stock awards granted			$ 0		$ 0
Restricted Stock \| One Year from the Vesting Commencement Date and Monthly Thereafter Over Three-year Vesting Period
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock vesting percentage							25.00%
Share-based compensation, vesting rights description					The Company granted 1,795,827 shares of its restricted stock in 2018, which vest 25% one year from the vesting commencement date and monthly thereafter over a three-year period.
Restricted Stock \| 25% One Year from Vesting Commencement Date
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock vesting period							1 year
Restricted Stock \| Monthly Thereafter Over Three-year Vesting Period
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock vesting period							3 years
2018 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, options granted that vest based on performance milestone		0
2021 Incentive Award Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance			16,170,804		16,170,804
Shares of common stock, authorized for issuance	15,150,000
Percentage of outstanding common stock maximum	5.00%
ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	1,260,000
Unrecognized compensation cost related to unvested stock option grants			$ 3,400,000		$ 3,400,000
Unrecognized compensation cost expected to be recognized as expense, period					1 year 8 months 12 days
Stock-based compensation			166,000	$ 278,000	$ 834,000	$ 278,000
Share-based payment arrangement, withheld on behalf of employees for future purchase			$ 261,000		$ 261,000			$ 102,000
Offering period	24 months
Purchase period	6 months
Shares issued under ESPP			0	0	150,642	0
ESPP \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of fair market value of common stock	85.00%