Stockholders' Equity - Stock-Based Compensation - Additional Information (Detail)	6 Months Ended
Jun. 30, 2019 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stockholders' equity, stock split, conversion ratio	0.75
Stock options exchanged \| shares	2,456,999
Stock options issued \| shares	1,842,746
Exercise price \| $ / shares	$ 0.62
Share-based compensation expense \| $	$ 84,000
Share-based compensation arrangement, vesting period	4 years
Unrecognized compensation costs \| $	$ 2,700,000
Weighted average period	1 year 4 months 24 days

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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The number of shares converted in a noncash (or part noncash) transaction. Noncash is defined as transactions during a period that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

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The number of new shares issued in the conversion of stock in a noncash (or part noncash) transaction. Noncash is defined as transactions during a period that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

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Unrecognized cost of unvested share-based compensation awards.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Agreed-upon price for the exchange of the underlying asset relating to the share-based payment award.

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Ratio applied to the conversion of stock split, for example but not limited to, one share converted to two or two shares converted to one.

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