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Stock Based Compensation - Stock Option Activity Under Equity Incentive Plan (Detail) (USD $)
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3 Months Ended |
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Mar. 31, 2015
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| Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] | |
| Number of Shares, Outstanding Beginning Balance | 8,168,942us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber |
| Number of Shares, Granted | 1,911,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross |
| Number of Shares, Exercised | (61,456)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised |
| Number of Shares, Forfeitures | (25,770)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod |
| Number of Shares, Outstanding Ending Balance | 9,993,216us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber |
| Number of Shares, Vested and expected to vest | 9,878,829us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber |
| Number of Shares, Exercisable | 5,521,561us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber |
| Weighted-Average Exercise Price, Outstanding at beginning of period | $ 3.69us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice |
| Weighted-Average Exercise Price, Granted | $ 4.42us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice |
| Weighted-Average Exercise Price, Exercised | $ 1.83us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice |
| Weighted-Average Exercise Price, Forfeitures | $ 5.15us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice |
| Weighted-Average Exercise Price, Outstanding at end of period | $ 3.83us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice |
| Weighted-Average Exercise Price, Vested and expected to vest | $ 3.83us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice |
| Weighted-Average Exercise Price, Exercisable | $ 3.33us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice |
| Weighted-Average Remaining Contractual Term, Outstanding | 7 years 6 months 11 days |
| Weighted-Average Remaining Contractual Term, Vested and expected to vest | 7 years 6 months 4 days |
| Weighted-Average Remaining Contractual Term, Exercisable | 6 years 3 months 22 days |
| Aggregate Intrinsic Value, Outstanding | $ 8,802,913us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue |
| Aggregate Intrinsic Value, Vested and expected to vest | 8,787,468us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue |
| Aggregate Intrinsic Value, Exercisable | $ 8,010,861us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1 |
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- Details
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- Definition
Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Gross number of share options (or share units) granted during the period. No definition available.
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- Definition
Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Number of options outstanding, including both vested and non-vested options. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount by which the current fair value of the underlying stock exceeds the exercise price of fully vested and expected to vest options outstanding. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be converted under the option plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
As of the balance sheet date, the weighted-average exercise price for outstanding stock options that are fully vested or expected to vest. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Weighted average remaining contractual term for fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Weighted average price at which option holders acquired shares when converting their stock options into shares. No definition available.
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- Definition
Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated. No definition available.
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- Definition
Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options. No definition available.
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- Definition
Number of share options (or share units) exercised during the current period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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