Share-Based Compensation - Summary of Assumptions Used for Valuation of Fair Value of Stock (Detail)	9 Months Ended	12 Months Ended
Sep. 30, 2021	Dec. 31, 2020
Black-Scholes Option-Pricing Model [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Risk-free interest rate, minimum	0.40%
Risk-free interest rate, maximum	1.10%
Expected volatility	90.00%
Expected dividend yield	0.00%
Third Party Valuation [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Risk-free interest rate		0.13%
Expected time to liquidity event in years		2 years
Expected volatility		90.00%
Expected dividend yield		0.00%
Minimum [Member] \| Black-Scholes Option-Pricing Model [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Expected term in years	5 years 3 months 18 days
Maximum [Member] \| Black-Scholes Option-Pricing Model [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Expected term in years	6 years 1 month 6 days

Share Based Compensation By Share Based Payment Arrangement Expected Liquidity Time.

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- Definition

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.

+ References

No definition available.

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- Definition

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

+ References

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- Definition

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

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- Definition

The maximum risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

No definition available.

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- Definition

The minimum risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

No definition available.

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- Definition

Rate of weighted-average expected volatility for award under share-based payment arrangement.

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- Definition

Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(i)
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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
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-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=122041274&loc=d3e301413-122809

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