Stock Based Compensation (Additional Information) (Detail) $ / shares in Units, $ in Thousands	9 Months Ended
Sep. 30, 2015 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average exercise price, granted \| $ / shares	$ 1.14
Averages contractual term	10 years
Estimated annualized forfeiture rate for options granted to employees	15.00%
Estimated annualized forfeiture rate for options granted to senior management	8.00%
Unrecognized compensation cost \| $	$ 4,815
Operating expenses weighted average period	2 years 4 months 2 days
Shares subject to outstanding common stock options granted	3,682,000
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Average vesting term	4 years
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Average vesting term	6 years
2007 Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock reserved for issuance	26,500,000
Shares subject to outstanding common stock options granted	11,188,000
Shares available for future grants	10,251,000
Vesting periods of options granted	4 years
Options expire from date of grant	10 years
Closing price of the Company's common stock \| $ / shares	$ 1.58

Closing price of common stock.

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Employee Service Share Based Compensation Unrecognized Compensation Costs

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Employee Service Share Based Compensation Unrecognized Compensation Costs Weighted Average Period Of Recognition

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Estimated annualized forfeiture rate for options granted to employees.

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Estimated annualized forfeiture rate for options granted to senior management.

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Share Based Compensation Arrangement By Share Based Payment Award Expiration Period

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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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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

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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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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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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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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 remaining contractual term for fully vested and expected to vest options that are exercisable or convertible, 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 of outstanding stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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