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Income Taxes (Details 2) (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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Mar. 31, 2013
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| NOL and tax credit carry forwards for federal and state income tax purposes | |||
| Period of time from grant date during which a tax benefit may be generated from a premature disposition of option shares exercised | 2 years | ||
| Period of time from exercise date during which a tax benefit may be generated from a premature disposition of option shares exercised | 1 year | ||
| Federal and state NOL carryforwards generated by disqualifying dispositions of stock options and exercises of nonqualified stock options | $ 27,700,000cpst_FederalAndStateNetOperatingLossCarryforwardsGeneratedByDisqualifyingDispositionsOfStockOptionsAndExercisesOfNonqualifiedStockOptions | ||
| Tax benefits associated with the stock options excluded from the provision for income taxes and credited directly to additional paid-in-capital | 10,000,000us-gaap_IncomeTaxEffectsAllocatedDirectlyToEquityEmployeeStockOptions | ||
| Other disclosures | |||
| Interest or penalties related to unrecognized tax benefits | 0us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued | 0us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued | |
| Unrecognized tax benefits, that if recognized, would affect the effective tax rate | 2,600,000us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate | 2,400,000us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate | |
| Reconciliation of the beginning and ending amount of total gross unrecognized tax benefits | |||
| Balance at the beginning of the period | 2,441,000us-gaap_UnrecognizedTaxBenefits | 2,418,000us-gaap_UnrecognizedTaxBenefits | 2,148,000us-gaap_UnrecognizedTaxBenefits |
| Gross decrease related to prior year tax positions | (93,000)us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions | (100,000)us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions | |
| Gross increase related to prior year tax positions | 11,000us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions | 1,000us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions | 222,000us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions |
| Gross increase related to current year tax positions | 112,000us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions | 115,000us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions | 148,000us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions |
| Balance at the end of the period | 2,564,000us-gaap_UnrecognizedTaxBenefits | 2,441,000us-gaap_UnrecognizedTaxBenefits | 2,418,000us-gaap_UnrecognizedTaxBenefits |
| Maximum | |||
| NOL and tax credit carry forwards for federal and state income tax purposes | |||
| Annual limitation amount on utilization of the NOLs and tax credits |
57,300,000cpst_AnnualLimitationAmountOnNetOperatingLossesAndTaxCreditsUtilization / us-gaap_RangeAxis = us-gaap_MaximumMember |
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| Federal | |||
| NOL and tax credit carry forwards for federal and state income tax purposes | |||
| Deferred tax assets related to research and development credits |
9,700,000us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch / us-gaap_IncomeTaxAuthorityAxis = us-gaap_InternalRevenueServiceIRSMember |
9,200,000us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch / us-gaap_IncomeTaxAuthorityAxis = us-gaap_InternalRevenueServiceIRSMember |
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| NOL |
625,918,000us-gaap_OperatingLossCarryforwards / us-gaap_IncomeTaxAuthorityAxis = us-gaap_InternalRevenueServiceIRSMember |
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| Tax credit carry forwards |
9,684,000us-gaap_TaxCreditCarryforwardAmount / us-gaap_IncomeTaxAuthorityAxis = us-gaap_InternalRevenueServiceIRSMember |
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| State | |||
| NOL and tax credit carry forwards for federal and state income tax purposes | |||
| Deferred tax assets related to research and development credits |
9,500,000us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch / us-gaap_IncomeTaxAuthorityAxis = us-gaap_StateAndLocalJurisdictionMember |
9,600,000us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch / us-gaap_IncomeTaxAuthorityAxis = us-gaap_StateAndLocalJurisdictionMember |
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| NOL |
202,275,000us-gaap_OperatingLossCarryforwards / us-gaap_IncomeTaxAuthorityAxis = us-gaap_StateAndLocalJurisdictionMember |
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| Tax credit carry forwards |
$ 9,176,000us-gaap_TaxCreditCarryforwardAmount / us-gaap_IncomeTaxAuthorityAxis = us-gaap_StateAndLocalJurisdictionMember |
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- Definition
Represents the amount of annual limitation on the utilization of net operating losses and tax credits. No definition available.
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- Definition
Represents the amount of federal and state NOL carry forwards generated by disqualifying dispositions of stock options and exercises of nonqualified stock options. No definition available.
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- Definition
Period of time from exercise date of options during which a tax benefit may be generated as a result of the premature disposition of shares acquired upon exercise of stock options. No definition available.
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- Definition
Period of time from grant date of options during which a tax benefit may be generated as a result of the premature disposition of shares acquired upon exercise of stock options. No definition available.
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- Definition
Amount before allocation of valuation allowances of deferred tax asset attributable to deductible research tax credit carryforwards. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The tax effects of employee stock option transactions that are recognized differently for financial reporting and tax purposes, occurring during the period and charged or credited directly to shareholders' equity. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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