Stock Incentive Plans and Stock-Based Compensation - Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Number of Shares
Outstanding as of January 1, 2021	16,664,000
Granted	4,813,000
Forfeited	(1,481,000)
Expired	(299,000)
Exercised	(1,203,845)	(1,623,460)
Outstanding as of December 31, 2021	18,493,000	16,664,000
Exercisable as of December 31, 2021	12,487,000
Vested and expected to vest as of December 31, 2021	18,193,000
Available for future grant as of December 31, 2021	13,229,000
Weighted Average Exercise Price
Outstanding as of January 1, 2021	$ 8.00
Granted	5.12
Forfeited	10.88
Expired	12.04
Exercised	2.43
Outstanding as of December 31, 2021	7.32	$ 8.00
Exercisable as of December 31, 2021	6.81
Vested and expected to vest as of December 31, 2021	$ 7.30
Weighted Average Remaining Contractual Term
Outstanding as of December 31, 2021	6 years 4 months 24 days
Exercisable as of December 31, 2021	5 years 2 months 12 days
Vested and expected to vest as of December 31, 2021	6 years 3 months 18 days
Aggregate Intrinsic Value
Outstanding as of December 31, 2021	$ 7,762
Exercisable as of December 31, 2021	7,744
Vested and expected to vest as of December 31, 2021	$ 7,761

Share-based Compensation Arrangement by Share-based Payment Award, Options, Aggregate Intrinsic Value [Abstract]

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Share-based Compensation Arrangement by Share-based Payment Award, Options, Weighted Average Remaining Contractual Term [Abstract]

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted-average exercise price, at which grantee can acquire shares reserved for issuance, for fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of share options (or share units) exercised during the current period.

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