Share-Based Compensation - Summary of Valuation Assumptions Used (Detail)	9 Months Ended	12 Months Ended
Sep. 30, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	55.20%
Contractual term (in years)	4 years
2018 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, Minimum		56.51%
Risk-free interest rate, Minimum		0.86%
Contractual term (in years)		10 years
2019 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	54.88%
Risk-free interest rate (per annum)	0.79%
Exercise multiple	2.80
Contractual term (in years)	10 years
2020 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise multiple, Maximum	2.80
Exercise multiple, Minimum	2.20

Share-based compensation arrangement by share-based payment award, fair value assumptions, exercise multiple.

No definition available.

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- Definition

Share-based compensation arrangement by share-based payment award, fair value assumptions, exercise multiple, Maximum

+ References

No definition available.

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- Definition

Share-based compensation arrangement by share-based payment award, fair value assumptions, exercise multiple. Minimum

+ 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.

+ References

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- Definition

The estimated measure of the minimum 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.

+ References

No definition available.

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

+ References

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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

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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)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

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