Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation (Details 4)

v2.4.1.9
Stock-Based Compensation (Details 4) (USD $)
3 Months Ended 9 Months Ended 1 Months Ended 6 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2014
Dec. 31, 2013
May 31, 2014
item
Sep. 30, 2014
Mar. 31, 2014
Additional disclosure              
Stock-based compensation expense $ 571,000us-gaap_AllocatedShareBasedCompensationExpense $ 481,000us-gaap_AllocatedShareBasedCompensationExpense $ 1,795,000us-gaap_AllocatedShareBasedCompensationExpense $ 1,664,000us-gaap_AllocatedShareBasedCompensationExpense      
Number of preferred stock purchase right for each share of common stock     1cpst_PreferredStockNumberOfPurchaseRightsPerShareOfCommonStock        
Preferred stock, par value (in dollars per share) $ 0.001us-gaap_PreferredStockParOrStatedValuePerShare   $ 0.001us-gaap_PreferredStockParOrStatedValuePerShare       $ 0.001us-gaap_PreferredStockParOrStatedValuePerShare
Purchase price (in dollars per share) $ 10.00cpst_PreferredStockPurchasePricePerShare   $ 10.00cpst_PreferredStockPurchasePricePerShare        
Period following public announcement of beneficial ownership acquired by various persons resulting in rights becoming exercisable     10 days        
Beneficial ownership of common stock (as a percent)     20.00%cpst_BeneficialOwnershipOfCommonStockPercentage        
Period following commencement of tender offer or exchange offer that would result in acquisition of beneficial ownership various persons resulting in rights becoming exercisable     10 days        
Series A Junior Participating Preferred Stock              
Additional disclosure              
Preferred stock conversion basis     0.01cpst_PreferredStockConversionRatio
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesAPreferredStockMember
       
Restricted stock units              
Shares              
Nonvested, balance at the beginning of the period (in shares)     2,061,224us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
    2,061,224us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
 
Granted (in shares)     919,666us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
       
Vested and issued (in shares)     (796,575)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
       
Forfeited (in shares)     (63,300)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
       
Nonvested, balance at the end of the period (in shares) 2,121,015us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
  2,121,015us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
       
Awards expected to vest (in shares) 1,948,599cpst_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
  1,948,599cpst_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
       
Weighted Average Grant-Date Fair Value              
Nonvested restricted stock units outstanding at the beginning of the period (in dollars per share)     $ 1.11us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
    $ 1.11us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
 
Granted (in dollars per share)     $ 1.41us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
       
Vested and issued (in dollars per share)     $ 1.13us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
       
Forfeited (in dollars per share)     $ 1.25us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
       
Nonvested restricted stock units outstanding at the end of the period (in dollars per share) $ 1.23us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
  $ 1.23us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
       
Awards expected to vest (in dollars per share) $ 1.23cpst_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
  $ 1.23cpst_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
       
Additional disclosure              
Total fair value of units vested and issued 28,200us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
33,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
1,200,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
800,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
     
Stock-based compensation expense 300,000us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
300,000us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
900,000us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
800,000us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
     
Unrecognized compensation cost 1,600,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
  1,600,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
       
Weighted average period for recognizing compensation cost     2 years 3 months 18 days        
Weighted average grant date fair value of options granted during the period (in dollars per share) $ 0.98us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
$ 1.27us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
$ 1.41us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
$ 1.06us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
     
PRSU Program              
Shares              
Granted (in shares) 0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= cpst_PerformanceRestrictedStockUnitProgramMember
           
Additional disclosure              
Stock-based compensation expense     62,800us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= cpst_PerformanceRestrictedStockUnitProgramMember
    25,700us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= cpst_PerformanceRestrictedStockUnitProgramMember
 
Unrecognized compensation cost $ 200,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions
/ us-gaap_AwardTypeAxis
= cpst_PerformanceRestrictedStockUnitProgramMember
  $ 200,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions
/ us-gaap_AwardTypeAxis
= cpst_PerformanceRestrictedStockUnitProgramMember
       
Weighted average period for recognizing compensation cost     2 years 3 months 18 days        
Second performance measurement period term         3 years    
Number of performance measurement periods         2cpst_SharebasedCompensationArrangementBySharebasedPaymentAwardNumberOfPerformanceMeasurementPeriod
/ us-gaap_AwardTypeAxis
= cpst_PerformanceRestrictedStockUnitProgramMember
   
Vesting right percentage of awards that will vest after end of applicable performance measurement period         50.00%cpst_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentageThatWillVestAfterEndOfPerformanceMeasurementPeriod
/ us-gaap_AwardTypeAxis
= cpst_PerformanceRestrictedStockUnitProgramMember
   
Vesting right percentage of awards that will vest one year after end of performance measurement period         50.00%cpst_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentageThatWillVestOneYearAfterEndOfPerformanceMeasurementPeriod
/ us-gaap_AwardTypeAxis
= cpst_PerformanceRestrictedStockUnitProgramMember
   
Weighted average grant date fair value of options granted during the period (in dollars per share)     $ 1.56us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= cpst_PerformanceRestrictedStockUnitProgramMember
       
Non-employee director              
Weighted Average Grant-Date Fair Value              
Granted (in dollars per share) $ 0.81us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_TitleOfIndividualAxis
= us-gaap_DirectorMember
$ 1.16us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_TitleOfIndividualAxis
= us-gaap_DirectorMember
$ 1.11us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_TitleOfIndividualAxis
= us-gaap_DirectorMember
$ 1.18us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_TitleOfIndividualAxis
= us-gaap_DirectorMember
     
Additional disclosure              
Number of shares issued 36,259us-gaap_StockIssuedDuringPeriodSharesIssuedForServices
/ us-gaap_TitleOfIndividualAxis
= us-gaap_DirectorMember
25,316us-gaap_StockIssuedDuringPeriodSharesIssuedForServices
/ us-gaap_TitleOfIndividualAxis
= us-gaap_DirectorMember
79,080us-gaap_StockIssuedDuringPeriodSharesIssuedForServices
/ us-gaap_TitleOfIndividualAxis
= us-gaap_DirectorMember
73,478us-gaap_StockIssuedDuringPeriodSharesIssuedForServices
/ us-gaap_TitleOfIndividualAxis
= us-gaap_DirectorMember
     
Chief Executive Officer | PRSU Program              
Shares              
Granted (in shares)         200,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= cpst_PerformanceRestrictedStockUnitProgramMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_ChiefExecutiveOfficerMember