Stock-Based Compensation - Black-Scholes-Merton Option Pricing Model for Stock Options Granted (Detail)	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019
Share-based Payment Arrangement [Abstract]
Expected dividend yield	0.00%	0.00%
Weighted average expected volatility	51.00%	58.00%
Weighted average expected term (years)	6 years 25 days	5 years 11 months 8 days
Weighted average risk-free rate	1.14%	2.29%

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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.

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- Definition

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

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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.

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