Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity (Deficit) - Additional Information (Detail)

v2.4.1.9
Stockholders' Equity (Deficit) - Additional Information (Detail) (USD $)
 0 Months Ended 1 Months Ended 3 Months Ended
Feb. 18, 2015
Feb. 28, 2015
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2014
Class Of Warrant Or Right [Line Items]          
Common stock sold, shares 8,300,000us-gaap_StockIssuedDuringPeriodSharesNewIssues        
Warrants to purchase shares of common stock 8,300,000us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights        
Proceeds from issuance of common stock and warrants, net of offering expenses $ 28,100,000us-gaap_ProceedsFromIssuanceOfCommonStock   $ 28,514,000us-gaap_ProceedsFromIssuanceOfCommonStock $ 345,000us-gaap_ProceedsFromIssuanceOfCommonStock  
Initial exercise price of the warrants   $ 10.86thld_WarrantsInitialExercisePrice      
Maximum exercise price of warrants after adjustment date   $ 10.86thld_WarrantMaximumAdjustedExercisePrice      
Minimum exercise price of warrants after adjustment date   $ 3.62thld_WarrantMinimumAdjustedExercisePrice      
Term of warrant   5 years      
Company can force exercise of warrant if 20 day VWAP price exceeds   $ 18.00thld_WarrantsTwentyDayVWAPExceeds      
February 2015 Offering          
Class Of Warrant Or Right [Line Items]          
Warrants outstanding 8,300,000us-gaap_ClassOfWarrantOrRightOutstanding
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_FebruaryTwoThousandFifteenOfferingMember 		  8,300,000us-gaap_ClassOfWarrantOrRightOutstanding
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_FebruaryTwoThousandFifteenOfferingMember 		   
Warrant exercise price $ 10.86us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_FebruaryTwoThousandFifteenOfferingMember 		  $ 10.86us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_FebruaryTwoThousandFifteenOfferingMember 		   
February 2015 Offering | Warrants          
Class Of Warrant Or Right [Line Items]          
Initial fair value of warrants at issuance date classified as warrant liability 14,700,000thld_InitialFairValueOfWarrants
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_FebruaryTwoThousandFifteenOfferingMember
/ us-gaap_FinancialInstrumentAxis
= us-gaap_WarrantMember 		       
Change in fair value of common stock warrants     1,200,000us-gaap_FairValueAdjustmentOfWarrants
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_FebruaryTwoThousandFifteenOfferingMember
/ us-gaap_FinancialInstrumentAxis
= us-gaap_WarrantMember 		   
March 2011 Offering          
Class Of Warrant Or Right [Line Items]          
Warrants outstanding     3,846,165us-gaap_ClassOfWarrantOrRightOutstanding
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_MarchTwoThousandElevenOfferingMember 		  3,846,165us-gaap_ClassOfWarrantOrRightOutstanding
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_MarchTwoThousandElevenOfferingMember
Warrant exercise price     $ 2.46us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_MarchTwoThousandElevenOfferingMember 		  $ 2.46us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_MarchTwoThousandElevenOfferingMember
March 2011 Offering | Warrants          
Class Of Warrant Or Right [Line Items]          
Change in fair value of common stock warrants     $ 2,700,000us-gaap_FairValueAdjustmentOfWarrants
/ us-gaap_ClassOfWarrantOrRightAxis
= thld_MarchTwoThousandElevenOfferingMember
/ us-gaap_FinancialInstrumentAxis
= us-gaap_WarrantMember