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Fair Value Measurements Interest Rate Swap (Details) (USD $)
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12 Months Ended | |
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Mar. 31, 2015
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Mar. 31, 2014
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| Interest Rate Swap [Abstract] | ||
| Derivative, unhedged principal payment in period one | $ 5,200,000thr_DerivativeUnhedgedPrincipalPaymentinPeriodOne | |
| Derivative, unhedged principal payment in period two | 49,780,000thr_DerivativeUnhedgedPrincipalPaymentinPeriodTwo | |
| Derivative, Fixed Interest Rate | 3.12%us-gaap_DerivativeFixedInterestRate | |
| Unrealized Loss in Accumulated Other Comprehensive Loss, before Tax [Roll Forward] | ||
| Unrealized gain/(loss) at beginning of the period, before Tax | (125,000)thr_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesinNetGainLossfromCashFlowHedgesbeforeTax | 0thr_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesinNetGainLossfromCashFlowHedgesbeforeTax |
| Add: gain/(loss) from change in fair value of cash flow hedge, before Tax | (1,755,000)us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax | (1,060,000)us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax |
| Add: non-fair value derivative asset transferred into accumulated other comprehensive income, before Tax | (325,000)thr_OtherComprehensiveIncomeLossDerivativeAssetsTransferredintoAOCICarryingValuebeforeTax | |
| Less: loss reclassified into earnings from effective hedge, before Tax | (1,090,000)thr_InterestRateCashFlowHedgeGainLossReclassifiedtoEarningsbeforeTax | (1,226,000)thr_InterestRateCashFlowHedgeGainLossReclassifiedtoEarningsbeforeTax |
| Less: ineffective portion of hedge transferred into earnings, before Tax | (44,000)thr_DerivativeInstrumentsGainLossRecognizedinIncomeIneffectivePortionandAmountExcludedfromEffectivenessTestingbeforeTax | (34,000)thr_DerivativeInstrumentsGainLossRecognizedinIncomeIneffectivePortionandAmountExcludedfromEffectivenessTestingbeforeTax |
| Unrealized loss at end of the period, before Tax | (746,000)thr_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesinNetGainLossfromCashFlowHedgesbeforeTax | (125,000)thr_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesinNetGainLossfromCashFlowHedgesbeforeTax |
| Unrealized Loss in Accumulated Other Comprehensive Loss, Tax [Roll Forward] | ||
| Unrealized gain/(loss) at beginning of the period, tax | (44,000)thr_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesinNetGainLossfromCashFlowHedgesTax | 0thr_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesinNetGainLossfromCashFlowHedgesTax |
| Add: gain/(loss) from change in fair value of cash flow hedge, tax | (614,000)us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax | (371,000)us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax |
| Add: non-fair value derivative asset transferred into accumulated other comprehensive income, tax | 114,000thr_OtherComprehensiveIncomeLossDerivativeAssetsTransferredintoAOCICarryingValueTax | |
| Less: loss reclassified into earnings from effective hedge, tax | (382,000)thr_InterestRateCashFlowHedgeGainLossReclassifiedtoEarningsTax | (429,000)thr_InterestRateCashFlowHedgeGainLossReclassifiedtoEarningsTax |
| Less: ineffective portion of hedge transferred into earnings, tax | (15,000)thr_DerivativeInstrumentsGainLossRecognizedinIncomeIneffectivePortionandAmountExcludedfromEffectivenessTestingTax | (12,000)thr_DerivativeInstrumentsGainLossRecognizedinIncomeIneffectivePortionandAmountExcludedfromEffectivenessTestingTax |
| Unrealized loss at end of the period, tax | (261,000)thr_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesinNetGainLossfromCashFlowHedgesTax | (44,000)thr_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesinNetGainLossfromCashFlowHedgesTax |
| Unrealized Loss In Accumulated Other Comprehensive Loss, Net of Tax [Roll Forward] | ||
| Unrealized gain/(loss) at beginning of the period | (81,000)us-gaap_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax | 0us-gaap_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax |
| Add: gain/(loss) from change in fair value of cash flow hedge | (1,141,000)us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax | (689,000)us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax |
| Add: non-fair value derivative asset transferred into accumulated other comprehensive income | (211,000)thr_OtherComprehensiveIncomeLossDerivativeAssetsTransferredintoAOCICarryingValue | |
| Less: loss reclassified into earnings from effective hedge | (708,000)us-gaap_InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet | (797,000)us-gaap_InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet |
| Less: ineffective portion of hedge transferred into earnings | (29,000)us-gaap_DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet | (22,000)us-gaap_DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet |
| Unrealized loss at end of the period | $ (485,000)us-gaap_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax | $ (81,000)us-gaap_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax |
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- Definition
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, before Tax No definition available.
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- Definition
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Tax No definition available.
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- Definition
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, before Tax No definition available.
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- Definition
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Tax No definition available.
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- Definition
Derivative, Unhedged Principal Payment in Period One No definition available.
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- Definition
Derivative, Unhedged Principal Payment in Period Two No definition available.
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- Definition
Interest Rate Cash Flow Hedge Gain (Loss) Reclassified to Earnings, before Tax No definition available.
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- Definition
Interest Rate Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Tax No definition available.
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- Details
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- Definition
Other Comprehensive Income Loss , Derivative Assets Transferred into AOCI, Carrying Value No definition available.
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Other Comprehensive Income Loss , Derivative Assets Transferred into AOCI, Carrying Value, before Tax No definition available.
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- Definition
Other Comprehensive Income Loss , Derivative Assets Transferred into AOCI, Carrying Value, Tax No definition available.
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- Details
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- Details
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- Details
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- Definition
Accumulated change, net of tax, in accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Includes an entity's share of an equity investee's Increase or Decrease in deferred hedging gains or losses. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Fixed interest rate related to the interest rate derivative. No definition available.
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- Definition
The portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments representing (a) the amount of the hedge ineffectiveness and (b) the amount, if any, excluded from the assessment of hedge effectiveness. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The amount of net gains or losses on interest rate cash flow hedges reclassified during the period to earnings from accumulated other comprehensive income upon the hedged transaction affecting earnings. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount before tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount after tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount of tax expense (benefit), before reclassification adjustments, related to increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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