Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity (Deficit) - Outstanding Warrants Valuation Assumption (Detail)

v2.4.1.9
Stockholders' Equity (Deficit) - Outstanding Warrants Valuation Assumption (Detail) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
October 2009 Offering    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Risk-free interest rate   0.13%us-gaap_FairValueAssumptionsRiskFreeInterestRate
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_OctoberTwoThousandNineOfferingMember
Expected life (in years)   9 months 4 days
Dividend yield   0.00%us-gaap_FairValueAssumptionsExpectedDividendRate
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_OctoberTwoThousandNineOfferingMember
Volatility   49.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_OctoberTwoThousandNineOfferingMember
Stock price   $ 4.67us-gaap_SharePrice
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_OctoberTwoThousandNineOfferingMember
March 2011 Offering    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Risk-free interest rate 0.67%us-gaap_FairValueAssumptionsRiskFreeInterestRate
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_MarchTwoThousandElevenOfferingMember
0.78%us-gaap_FairValueAssumptionsRiskFreeInterestRate
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_MarchTwoThousandElevenOfferingMember
Expected life (in years) 1 year 2 months 16 days 2 years 2 months 16 days
Dividend yield 0.00%us-gaap_FairValueAssumptionsExpectedDividendRate
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_MarchTwoThousandElevenOfferingMember
0.00%us-gaap_FairValueAssumptionsExpectedDividendRate
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_MarchTwoThousandElevenOfferingMember
Volatility 49.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_MarchTwoThousandElevenOfferingMember
88.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_MarchTwoThousandElevenOfferingMember
Stock price $ 3.18us-gaap_SharePrice
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_MarchTwoThousandElevenOfferingMember
$ 4.67us-gaap_SharePrice
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_MarchTwoThousandElevenOfferingMember