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Summary of Stock Option Activity (Detail) (USD $)
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12 Months Ended | ||
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Dec. 31, 2014
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Dec. 31, 2013
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Dec. 31, 2012
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| Number of Options | |||
| Number of Options, Beginning balance | 14,584us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber | 22,022us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber | 82,166us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber |
| Number of Options, Exercised | (14,584)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised | (7,438)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised | (60,144)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised |
| Number of Options, Ending balance | 14,584us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber | 22,022us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber | |
| Number of Options, Vested at December 31 | 14,584us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber | 22,022us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber | |
| Weighted Average Exercise Price | |||
| Weighted Average Exercise Price, Beginning balance | $ 7.63us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice | $ 7.63us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice | $ 7.63us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice |
| Weighted Average Exercise Price, Exercised | $ 7.63us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice | $ 7.63us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice | $ 7.63us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice |
| Weighted Average Exercise Price, Ending balance | $ 7.63us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice | $ 7.63us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice | |
| Weighted Average Exercise Price, Vested options | $ 7.63us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice | $ 7.63us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice | |
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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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- Details
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| X | ||||||||||
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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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- Details
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| X | ||||||||||
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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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| X | ||||||||||
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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 price at which option holders acquired shares when converting their stock options into shares. 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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