Quarterly report pursuant to Section 13 or 15(d)

Long-Term Debt (Details)

v2.4.1.9
Long-Term Debt (Details) (USD $)
9 Months Ended 0 Months Ended
Dec. 31, 2014
Dec. 31, 2013
May 20, 2013
Jun. 11, 2014
Jun. 10, 2014
Mar. 31, 2014
Debt Instrument [Line Items]            
Less current portion $ (13,500,000)us-gaap_SecuredDebtCurrent         $ (13,500,000)us-gaap_SecuredDebtCurrent
Long-term debt, noncurrent 97,875,000us-gaap_SecuredLongTermDebt         108,000,000us-gaap_SecuredLongTermDebt
Premiums paid on redemptions 0us-gaap_RedemptionPremium (15,485,000)us-gaap_RedemptionPremium        
Issuance costs associated with revolving line of credit and long term debt 290,000us-gaap_DebtIssuanceCosts          
9.500% Senior Secured Notes, due May 2017            
Debt Instrument [Line Items]            
Variable Rate Term Loan, due April 2019     118,145,000us-gaap_SecuredDebt
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember
     
Debt Instrument, interest rate, stated percentage 2.1875%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember
         
Premiums paid on redemptions     15,485,000us-gaap_RedemptionPremium
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember
     
Deferred debt amortization     4,010,000us-gaap_AmortizationOfDeferredCharges
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember
     
Loans Payable            
Debt Instrument [Line Items]            
Variable Rate Term Loan, due April 2019           121,500,000us-gaap_SecuredDebt
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LoansPayableMember
Debt Instrument, interest rate, stated percentage 2.1875%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LoansPayableMember
         
Revolving credit facility            
Debt Instrument [Line Items]            
Maximum borrowing capacity 60,000,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_RevolvingCreditFacilityMember
         
Debt instrument, interest rate, decrease (percentage)       0.25%us-gaap_DebtInstrumentInterestRateIncreaseDecrease
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_RevolvingCreditFacilityMember
   
Line of credit facility, decrease in periodic payment (as a percentage)       0.05%thr_LineofCreditFacilityIncreaseDecreasePeriodicPaymentPercentage
/ 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
 
Annual commitment fee on unutilized commitments (as a percent) 0.30%us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_RevolvingCreditFacilityMember
         
Line of credit facility, commitment fee percentage 0.125%us-gaap_LineOfCreditFacilityCommitmentFeePercentage
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_RevolvingCreditFacilityMember
         
Outstanding borrowings 0us-gaap_LinesOfCreditCurrent
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_RevolvingCreditFacilityMember
         
Revolving credit facility | Thermon Industries, Inc.            
Debt Instrument [Line Items]            
Capacity available under credit facility 59,137,000us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
/ dei_LegalEntityAxis
= thr_ThermonIndustriesIncMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_RevolvingCreditFacilityMember
         
Interest rate at period end (as a percent) 2.1875%us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd
/ dei_LegalEntityAxis
= thr_ThermonIndustriesIncMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_RevolvingCreditFacilityMember
         
London Interbank Offered Rate (LIBOR)            
Debt Instrument [Line Items]            
Interest rate in addition to LIBOR rate 1.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_VariableRateAxis
= us-gaap_LondonInterbankOfferedRateLIBORMember
         
Canadian Deposit Offer Rate            
Debt Instrument [Line Items]            
Interest rate in addition to LIBOR rate 1.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_VariableRateAxis
= thr_CanadianDepositOfferRateMember
         
Minimum | Base Rate            
Debt Instrument [Line Items]            
Interest rate in addition to LIBOR rate 0.50%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_VariableRateAxis
= us-gaap_BaseRateMember
         
Maximum | Base Rate            
Debt Instrument [Line Items]            
Interest rate in addition to LIBOR rate 1.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_VariableRateAxis
= us-gaap_BaseRateMember
         
Through March 31, 2016 | Loans Payable            
Debt Instrument [Line Items]            
Repayments of Notes Payable 1,125,000us-gaap_RepaymentsOfNotesPayable
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LoansPayableMember
/ thr_PeriodAxis
= thr_PeriodOneMember
         
Last Two Years Of Loan | Loans Payable            
Debt Instrument [Line Items]            
Repayments of Notes Payable 1,688,000us-gaap_RepaymentsOfNotesPayable
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LoansPayableMember
/ thr_PeriodAxis
= thr_PeriodTwoMember
         
Due in April 2018 | Loans Payable            
Debt Instrument [Line Items]            
Repayments of Notes Payable $ 40,500,000us-gaap_RepaymentsOfNotesPayable
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LoansPayableMember
/ thr_PeriodAxis
= thr_PeriodThreeMember