Annual report pursuant to Section 13 and 15(d)

Equity Incentive Plans and Stock Based Compensation - Assumptions of Equity-Based Payments to Non-Employees (Detail)

v2.4.1.9
Equity Incentive Plans and Stock Based Compensation - Assumptions of Equity-Based Payments to Non-Employees (Detail) (Non-employee Stock-based Compensation Expense)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Non-employee Stock-based Compensation Expense
     
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Risk-free interest rate 2.52%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_PlanNameAxis
= thld_NonEmployeeStockBasedCompensationMember
2.51%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_PlanNameAxis
= thld_NonEmployeeStockBasedCompensationMember
1.93%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_PlanNameAxis
= thld_NonEmployeeStockBasedCompensationMember
Expected life (in years) 10 years 10 years 10 years
Expected volatility 97.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_PlanNameAxis
= thld_NonEmployeeStockBasedCompensationMember
100.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_PlanNameAxis
= thld_NonEmployeeStockBasedCompensationMember
101.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_PlanNameAxis
= thld_NonEmployeeStockBasedCompensationMember