Summary of Outstanding and Exercisable Options (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended
Jun. 30, 2012
Shares
Outstanding at June 30, 2012	888,328
Exercisable at June 30, 2012	536,302
Weighted-Average Exercise Price
Outstanding at June 30, 2012	$ 8.65
Exercisable at June 30, 2012	$ 9.17
Weighted-average remaining contractual term (years)
Outstanding at June 30, 2012	6 years 2 months 12 days
Exercisable at June 30, 2012	4 years 7 months 6 days
Aggregate intrinsic value
Outstanding at June 30, 2012	$ 4,388
Exercisable at June 30, 2012	$ 2,392

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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.

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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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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.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of options outstanding.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including 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 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.

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