Annual report pursuant to Section 13 and 15(d)

Income Taxes - Schedule of Reconciliation of Income Taxes at Statutory Federal Income Tax Rate to Net Income Taxes (Detail)

v2.4.1.9
Income Taxes - Schedule of Reconciliation of Income Taxes at Statutory Federal Income Tax Rate to Net Income Taxes (Detail) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Income Tax Disclosure [Abstract]      
U.S. federal taxes (benefit) at statutory rate $ (7,407)us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate $ (9,592)us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate $ (24,186)us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate
State federal income tax benefit (571)us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes (1,794)us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes (1,160)us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes
Unutilized (utilized) net operating losses 9,809thld_IncomeTaxReconciliationUnutilizedUtilizedNetOperatingLosses 9,747thld_IncomeTaxReconciliationUnutilizedUtilizedNetOperatingLosses 7,455thld_IncomeTaxReconciliationUnutilizedUtilizedNetOperatingLosses
Stock-based compensation 730us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost 486us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost 288us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost
Research and development credits (952)us-gaap_IncomeTaxReconciliationTaxCreditsResearch (1,416)us-gaap_IncomeTaxReconciliationTaxCreditsResearch  
Tax assets not benefited 1,322thld_IncomeTaxReconciliationTaxAssetsNotBenefited 1,926thld_IncomeTaxReconciliationTaxAssetsNotBenefited 143thld_IncomeTaxReconciliationTaxAssetsNotBenefited
Nondeductible warrant expense (3,177)us-gaap_IncomeTaxReconciliationNondeductibleExpenseOther 790us-gaap_IncomeTaxReconciliationNondeductibleExpenseOther 17,414us-gaap_IncomeTaxReconciliationNondeductibleExpenseOther
Other 44us-gaap_IncomeTaxReconciliationOtherAdjustments 55us-gaap_IncomeTaxReconciliationOtherAdjustments 46us-gaap_IncomeTaxReconciliationOtherAdjustments
Total $ (202)us-gaap_IncomeTaxExpenseBenefit $ 202us-gaap_IncomeTaxExpenseBenefit