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Stock Based Compensation - Additional Information (Detail) (USD $)
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3 Months Ended | 6 Months Ended | 1 Months Ended | 6 Months Ended | 1 Months Ended | |||||||||
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Jun. 30, 2012
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Jun. 30, 2011
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Jun. 30, 2012
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Jun. 30, 2011
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Dec. 31, 2011
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Jun. 30, 2012
Restricted Stock
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Dec. 31, 2011
Restricted Stock
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Aug. 31, 2008
2008 Plan
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Jun. 30, 2012
2008 Plan
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Jun. 30, 2011
2008 Plan
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Jun. 30, 2012
2008 Plan
Restricted Stock
Minimum
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Jun. 30, 2012
2008 Plan
Restricted Stock
Maximum
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Aug. 31, 2008
Previously Approved Plans
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Jun. 30, 2012
Previously Approved Plans
Restricted Stock
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||||||||||||
| Shares initially authorized for issuance under equity incentive plan | 300,000 | |||||||||||||
| Additional shares authorized for issuance under equity incentive plan | 41,500 | |||||||||||||
| Shares ceased to be issuable | 41,500 | |||||||||||||
| Outstanding options to purchase shares of common stock | 436,001 | 436,001 | 546,001 | |||||||||||
| Unvested restricted shares outstanding | 319,001 | |||||||||||||
| Outstanding shares remained available for future grants | 17,666 | |||||||||||||
| Restricted shares outstanding | 319,001 | 232,501 | 0 | |||||||||||
| Share-base compensation expense | $ 120,000 | $ 102,000 | $ 219,000 | $ 225,000 | ||||||||||
| Vesting period | 3 years | 4 years | ||||||||||||
| Unrecognized compensation cost related to the nonvested service-conditioned restricted shares | $ 821,210 | $ 887,158 | ||||||||||||
| Unrecognized compensation costs are expected to be recognized over a weighted average period (years) | 2 years 1 month 6 days | 2 years 4 months 24 days | ||||||||||||