Stock-Based Compensation - Additional Information (Detail)	3 Months Ended	6 Months Ended
Jun. 30, 2018 USD ($) $ / shares shares	Jun. 30, 2018 USD ($)
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate number of shares granted to awards, share-based compensation arrangements \| shares	4,344,758
Weighted average exercise price of the stock options granted \| $ / shares	$ 1.91
Vesting period	4 years
Fair value of stock granted, share-based compensation arrangements	$ 6,300,000
Weighted average grant date fair value of the stock options granted \| $ / shares	$ 1.46
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units issued \| shares	391,200
Fair value of Restricted stock options granted	$ 747,192
Weighted average grant date fair value of the stock options granted \| $ / shares	$ 1.91
Unrecognized compensation expense related to non-option	$ 2,300,000	$ 2,300,000
Options vest over vesting period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to options	9,000,000	9,000,000
Performance-based Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to options	2,000,000	2,000,000
Compensation cost	$ 400,000	$ 1,400,000

Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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Unrecognized cost of unvested options awarded to employees as compensation.

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

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Amount of capitalized and expensed compensation cost from equity-based compensation arrangements.

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Value, before forfeitures, of stock or other type of equity granted of any equity-based compensation plan other than an employee stock ownership plan (ESOP).

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Number of shares issued during the period related to Restricted Stock Awards, net of any shares forfeited.

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