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Fair Value Measurements and Marketable Securities - Additional Information (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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| Schedule Of Available For Sale Securities [Line Items] | |||
| Recognized realized gains | $ 3,000us-gaap_AvailableForSaleSecuritiesGrossRealizedGains | $ 5,000us-gaap_AvailableForSaleSecuritiesGrossRealizedGains | |
| Recognized realized losses | 0us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses | 0us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses | |
| Realized gain or losses | 0us-gaap_AvailableForSaleSecuritiesGrossRealizedGainLossNet | ||
| Realized gains and losses related to unrealized gains and losses in accumulated comprehensive income | $ 0thld_RealizedGainsLossesFromUnrealizedGainsLossesComprehensiveIncome | $ 0thld_RealizedGainsLossesFromUnrealizedGainsLossesComprehensiveIncome | |
| Weighted average maturity for available for sale securities | 4 months | ||
| Shares of common stock to be purchased with warrants | 3,800,000us-gaap_ClassOfWarrantOrRightOutstanding | ||
| Maximum | |||
| Schedule Of Available For Sale Securities [Line Items] | |||
| Available for sale securities, longest maturity date | 2015-09 | ||
| X | ||||||||||
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- Definition
Available for sale securities maturities month. No definition available.
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- Definition
Realized gains and losses related to unrealized gains and losses in accumulated comprehensive income. No definition available.
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- Definition
Weighted average maturity for available for sale securities. No definition available.
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- Definition
This item represents the difference between the gross realized gains and losses realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
This item represents the gross loss realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
Number of warrants or rights outstanding. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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- Details
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