Quarterly report pursuant to Section 13 or 15(d)

Commitments and Contingencies (Details)

v2.4.1.9
Commitments and Contingencies (Details) (USD $)
In Thousands, unless otherwise specified
 9 Months Ended
Dec. 31, 2014
Mar. 31, 2014
Loss Contingencies [Line Items]    
Totaled arrangements under letter of credit guarantees and performance bonds securing performance obligations $ 16,234us-gaap_GuaranteeObligationsMaximumExposure  
Guarantee obligations secured by cash deposits 1,380thr_GuaranteeObligationsSecuredByCashDeposits  
Guarantee obligations represented by a reduction of the available amount of the company's short term and long term revolving lines of credit 863thr_GuaranteeObligationsRepresentedByReductionOfAvailableAmountOfLinesOfCredit  
Cash deposits pledged as collateral on performance bonds and letters of credit 1,380thr_GuaranteeObligationsCashDepositsPledgedAsCollateral 1,307thr_GuaranteeObligationsCashDepositsPledgedAsCollateral
Indian Custom Bonds Outstanding 4,626thr_IndianCustomBondsOutstanding  
Russian Tax Authority    
Loss Contingencies [Line Items]    
Payments for legal settlements $ 140us-gaap_PaymentsForLegalSettlements
/ us-gaap_IncomeTaxAuthorityAxis
= thr_RussianTaxAuthorityMember