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           Income Taxes - Additional Information (Detail) (USD $) 
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        3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
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           Jun. 30, 2013 
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           Jun. 30, 2012 
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           Jun. 30, 2013 
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           Jun. 30, 2012 
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| Income Tax Disclosure [Abstract] | ||||
| Provision for income taxes | $ 131,000 | $ 130,000 | $ 211,000 | $ 191,000 | 
| Unrecognized tax benefits | 100,000 | |||
| Period of change of unrecognized tax benefits | 12 months | |||
| Accrued interest and penalties | 0 | 0 | ||
| Taxable Income Adjustment from Tax Examination | $ 0 | $ 0 | ||
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- Definition 
          Period of change of unrecognized tax benefits. No definition available. 
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- Definition 
          Adjustment to taxable income arising from a tax examination. No definition available. 
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- Details 
          
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- Definition 
          The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          This element represents the total of accruals as of the date of the statement of financial position for interest recognized for an underpayment of income taxes computed by applying the applicable statutory rate of interest to the difference between a tax position recognized for financial reporting purposes and the amount previously taken or expected to be taken in a tax return of the entity and the amount of statutory penalties for a tax position claimed or expected to be claimed by the entity, in its tax return, that does not meet the minimum statutory threshold to avoid payment of penalties. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          The net amount of all increases and decreases in unrecognized tax benefits for the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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