Annual report pursuant to Section 13 and 15(d)

Long-Term Debt (Details)

v2.4.1.9
Long-Term Debt (Details) (USD $)
 0 Months Ended 3 Months Ended 12 Months Ended 0 Months Ended
Jun. 11, 2014
Jun. 30, 2013
Mar. 31, 2015
Mar. 31, 2014
Mar. 31, 2013
May 20, 2013
Jun. 10, 2014
Debt Instrument [Line Items]              
Less current portion     $ (13,500,000)us-gaap_SecuredDebtCurrent $ (13,500,000)us-gaap_SecuredDebtCurrent      
Long-term debt, noncurrent     94,500,000us-gaap_SecuredLongTermDebt 108,000,000us-gaap_SecuredLongTermDebt      
Debt Instrument, Interest Rate, Increase (Decrease)     (0.25%)us-gaap_DebtInstrumentInterestRateIncreaseDecrease        
Line of Credit Facility, Commitment Fee Percentage, Increase (Decrease) (0.05%)thr_LineofCreditFacilityCommitmentFeePercentageIncreaseDecrease            
Premium paid on redemption of senior secured notes     0us-gaap_RedemptionPremium (15,485,000)us-gaap_RedemptionPremium (630,000)us-gaap_RedemptionPremium    
Write off of Deferred Debt Issuance Cost   4,010,000us-gaap_WriteOffOfDeferredDebtIssuanceCost          
Derivative, Fixed Interest Rate     3.12%us-gaap_DerivativeFixedInterestRate        
Derivative, unhedged principal payment in period one     5,200,000thr_DerivativeUnhedgedPrincipalPaymentinPeriodOne        
Derivative, unhedged principal payment in period two     49,780,000thr_DerivativeUnhedgedPrincipalPaymentinPeriodTwo        
Loans Payable [Member]              
Debt Instrument [Line Items]              
Interest rate (as a percent)     2.19%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LoansPayableMember 		       
Long-term debt     108,000,000us-gaap_SecuredDebt
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LoansPayableMember 		121,500,000us-gaap_SecuredDebt
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LoansPayableMember 		     
Senior secured note [Member]              
Debt Instrument [Line Items]              
Deferred debt amortization     290,000us-gaap_DebtIssuanceCosts
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		       
Repayments of Notes Payable         21,000,000us-gaap_RepaymentsOfNotesPayable
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		118,145,000us-gaap_RepaymentsOfNotesPayable
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		 
Premium paid on redemption of senior secured notes         630,000us-gaap_RedemptionPremium
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		15,485,000us-gaap_RedemptionPremium
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		 
Write off of Deferred Debt Issuance Cost       871,000us-gaap_WriteOffOfDeferredDebtIssuanceCost
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		  4,010,000us-gaap_WriteOffOfDeferredDebtIssuanceCost
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		 
Revolving Credit Facility [Member]              
Debt Instrument [Line Items]              
Debt Instrument, Fee     .00125        
Maximum borrowing capacity     60,000,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_RevolvingCreditFacilityMember 		       
Maximum leverage ratio 2.75thr_DebtInstrumentCovenantComplianceMaximumLeverageRatio
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_RevolvingCreditFacilityMember 		          2.25thr_DebtInstrumentCovenantComplianceMaximumLeverageRatio
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_RevolvingCreditFacilityMember
Capacity available under credit facility     59,251,000us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_RevolvingCreditFacilityMember 		       
Outstanding borrowings     0us-gaap_LinesOfCreditCurrent
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_RevolvingCreditFacilityMember 		       
Annual commitment fee on unutilized commitments (as a percent)     0.30%us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_RevolvingCreditFacilityMember 		       
Revolving Credit Facility [Member] | Thermon Industries, Inc. [Member]              
Debt Instrument [Line Items]              
Interest rate at period end (as a percent)     2.19%us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd
/ dei_LegalEntityAxis
= thr_ThermonIndustriesIncMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_RevolvingCreditFacilityMember 		       
Period One [Member] | Loans Payable [Member]              
Debt Instrument [Line Items]              
Repayments of Notes Payable     1,125,000us-gaap_RepaymentsOfNotesPayable
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LoansPayableMember
/ thr_PeriodAxis
= thr_PeriodOneMember 		       
Period Two [Member] | Loans Payable [Member]              
Debt Instrument [Line Items]              
Repayments of Notes Payable     1,688,000us-gaap_RepaymentsOfNotesPayable
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LoansPayableMember
/ thr_PeriodAxis
= thr_PeriodTwoMember 		       
Period Three [Member] | Loans Payable [Member]              
Debt Instrument [Line Items]              
Repayments of Notes Payable     40,500,000us-gaap_RepaymentsOfNotesPayable
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LoansPayableMember
/ thr_PeriodAxis
= thr_PeriodThreeMember 		       
Senior Secured Notes, 9.5 Percent, Due May 2017 | Senior secured note [Member]              
Debt Instrument [Line Items]              
Interest rate (as a percent)     9.50%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= thr_SeniorSecuredNotes9.5PercentDueMay2017Member
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		       
Debt instrument, maturity date     May 31, 2017        
Variable Rate Term Loan, Due April 2018 | Loans Payable [Member]              
Debt Instrument [Line Items]              
Debt instrument, maturity date     Apr. 30, 2018        
Long-term debt     $ 108,000,000us-gaap_SecuredDebt
/ us-gaap_DebtInstrumentAxis
= thr_VariableRateTermLoanDueApril2018Member
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LoansPayableMember