Stockholders' Equity (Stock Option and RSU Activity) (Detail) shares in Thousands	6 Months Ended
Jun. 30, 2020 $ / shares shares
Number of options
Ending outstanding number (in shares)	6,327
Stock options and performance stock options
Number of options
Beginning outstanding number (in shares)	3,098
Granted (in shares)	3,309
Exercised (in shares)	(1)
Canceled/forfeited/expired (in shares)	(79)
Ending outstanding number (in shares)	6,327
Weighted average exercise price
Weighted average exercise price, beginning balance (in dollars per share) \| $ / shares	$ 1.17
Weighted average exercise price, Granted (in dollars per share) \| $ / shares	1.27
Weighted average exercise price, Exercised (in dollars per share) \| $ / shares	0.95
Weighted average exercise price, Canceled/forfeited/expired (in dollars per share) \| $ / shares	8.35
Weighted average exercise price, ending balance (in dollars per share) \| $ / shares	$ 1.14
Restricted Stock Units (RSUs)
Number of RSUs
Beginning balance (in shares)	129
Shares granted (in shares)	0
Shares vested (in shares)	(39)
Shares canceled in period (in shares)	(19)
Ending balance (in shares)	71
Weighted average grant date fair value
Beginning balance (usd per share) \| $ / shares	$ 1.50
Granted (usd per share) \| $ / shares	0
Vested (usd per share) \| $ / shares	1.50
Canceled/forfeited/expired (usd per share) \| $ / shares	1.50
Ending balance (usd per share) \| $ / shares	$ 1.50

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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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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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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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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For presentations that combine terminations, 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 or that expired.

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Weighted average price of options that were either forfeited or expired.

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

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

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

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

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