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- Definition

Class of warrant or right warrants expiration month and year.

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- Definition

Ownership interest, percentage of voting rights of stock.

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- Definition

Exercise price per share or per unit of warrants or rights outstanding.

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- Definition

Number of warrants or rights outstanding.

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Aggregate number of common shares reserved for future issuance.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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Weighted-average period over which cost not yet recognized is expected to be recognized for 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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Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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- Definition

Amount of cost to be recognized for option under share-based payment arrangement.

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- Definition

Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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- Definition

The number of grants made 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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- Definition

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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- Definition

Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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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

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.

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- Definition

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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- Definition

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

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No definition available.

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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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- Definition

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

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- Definition

Maximum number of shares that may be issued in accordance with the plan as a proportion of outstanding capital stock.

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Percentage of vesting of award under share-based payment arrangement.

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Period from grant date that an equity-based award expires, 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 exercisable or convertible options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the 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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- Definition

Purchase price of common stock expressed as a percentage of its fair value.

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Number of shares issued during the period as a result of an employee stock purchase plan.

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Stockholders' Equity - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	Sep. 28, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Weighted average grant date fair value per option granted (in dollars per share)			$ 1.73	$ 1.95
Number of shares available for issuance under the plan on the first day of each year	79,759,225		79,759,225		79,615,692
Warrants to Purchase Stock [Member] \| 2010 and 2012 Convertible Promissory Notes [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants outstanding (in shares)	102,070		102,070
Exercise price of warrants (in dollars per share)	$ 24.35		$ 24.35
Warrants term			10 years
Warrants expiration period			2024-11
Underwriter [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants outstanding (in shares)	16,500		16,500
Exercise price of warrants (in dollars per share)	$ 35.70		$ 35.70
Warrants term			10 years
Warrants expiration period			2024-11
Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for grant	27,967		27,967
Percentage of outstanding stock maximum			1.00%
Number of shares available for issuance under the plan on the first day of each year	55,936		55,936
Number of shares purchases by employees			0
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Ownership interest of voting rights of all classes of stock (percent)	10.00%		10.00%
2020 Inducement Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for grant	1,500,000		1,500,000
Number of shares reserved for issuance						1,500,000
Stock units granted			0
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Income tax benefits recognized from stock-based compensation	$ 0	$ 0	$ 0	$ 0
Number of options granted	219,310	452,650	3,387,810	452,650
Expected dividend yield			0.00%
Future stock-based compensation for unvested employee options granted and outstanding	$ 6,100,000		$ 6,100,000
Future stock-based compensation, requisite service period			3 years 9 months 18 days
Stock Options [Member] \| 2014 Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period			4 years
Number of shares available for grant	1,167,773		1,167,773
Number of options granted			3,387,810
Options outstanding at end of period	$ 19,000		$ 19,000
Stock Options [Member] \| 2014 Equity Incentive Plan [Member] \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of fair market value			110.00%
Stock Options [Member] \| 2014 Equity Incentive Plan [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Contractual term of option			10 years
ISOs [Member] \| 2014 Equity Incentive Plan [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Contractual term of option			5 years
Performance-Based Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of options granted	708,750		708,750
Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period			4 years
Stock units granted	39,463	16,461	61,273	703,718
Vesting percentage			100.00%
Weighted average grant-date fair value of all restricted stock units granted			$ 1.48	$ 3.81
Fair value of restricted stock units vested			$ 700,000	$ 0.1
Unrecognized stock based compensation expense	$ 1,700,000		$ 1,700,000
Weighted average remaining vesting period			2 years 7 months 6 days
Restricted Stock Units [Member] \| 2014 Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock units granted			61,273
Weighted average grant-date fair value of all restricted stock units granted			$ 1.48