Equity Incentive Awards - Summary of Stock Options Activity (Detail)	3 Months Ended
Mar. 31, 2019 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Options Outstanding [Roll Forward]
Number of Options, Beginning Balance \| shares	6,447,000
Number of Options, Options granted \| shares	1,875,000
Number of Options, Options exercised \| shares	(118,000)
Number of Options, Options cancelled \| shares	(235,000)
Number of Options, Ending Balance \| shares	7,969,000
Number of Options, Exercisable \| shares	3,760,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted-Average Exercise Price, Beginning Balance \| $ / shares	$ 5.83
Weighted-Average Exercise Price, Options granted \| $ / shares	3.61
Weighted-Average Exercise Price, Options exercised \| $ / shares	1.37
Weighted-Average Exercise Price, Options cancelled \| $ / shares	4.21
Weighted-Average Exercise Price, Ending Balance \| $ / shares	5.42
Weighted-Average Exercise Price, Exercisable \| $ / shares	$ 6.60

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

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-Publisher FASB
-Name Accounting Standards Codification
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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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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 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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Number of share options (or share units) exercised during the current period.

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