Annual report pursuant to Section 13 and 15(d)

Commitments and Contingencies (Details 3)

v2.4.1.9
Commitments and Contingencies (Details 3) (USD $)
In Millions, unless otherwise specified
12 Months Ended 0 Months Ended 1 Months Ended
Mar. 31, 2015
May 31, 2014
Sep. 30, 2010
kW
Other disclosures      
Cost to distributors for replacement of affected stock $ 0cpst_CostToDistributorsForReplacementOfAffectedStock    
DOE      
Commitments and Contingencies      
Projected cost of research, development and testing project   0.2cpst_ProjectedCostOfResearchDevelopmentAndTestingProject
/ dei_LegalEntityAxis
= cpst_DepartmentOfEnergyMember
 
Percentage Contribution by ORNL   100.00%cpst_PercentageContribution
/ dei_LegalEntityAxis
= cpst_DepartmentOfEnergyMember
 
Period of contract   19 months  
Cumulative amount of bill under contract 0.1cpst_CumulativeAmountOfBillToOtherPartyTowardsResearchDevelopmentAndTestingProject
/ dei_LegalEntityAxis
= cpst_DepartmentOfEnergyMember
   
Research, development and testing of a more efficient microturbine Combined Heat and Power (CHP) system      
Commitments and Contingencies      
Projected electrical efficiency of microturbine (as a percent)     42.00%cpst_PercentageOfProjectedElectricalEfficiencyOfMicroturbine
/ us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis
= cpst_ResearchDevelopmentAndTestingOfMoreEfficientMicroturbineMember
Power output of microturbine (in kW)     370cpst_PowerOutputOfMicroturbine
/ us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis
= cpst_ResearchDevelopmentAndTestingOfMoreEfficientMicroturbineMember
Projected cost of research, development and testing project     15.0cpst_ProjectedCostOfResearchDevelopmentAndTestingProject
/ us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis
= cpst_ResearchDevelopmentAndTestingOfMoreEfficientMicroturbineMember
Contribution by other party     5.0cpst_ContributionToBeMadeByOtherPartyTowardsResearchDevelopmentAndTestingProject
/ us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis
= cpst_ResearchDevelopmentAndTestingOfMoreEfficientMicroturbineMember
Expense to be incurred by the company in research and development     10.0cpst_ResearchAndDevelopmentExpenseToBeIncurredByEntity
/ us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis
= cpst_ResearchDevelopmentAndTestingOfMoreEfficientMicroturbineMember
Period of contract 5 years    
Cumulative amount of bill under contract $ 3.9cpst_CumulativeAmountOfBillToOtherPartyTowardsResearchDevelopmentAndTestingProject
/ us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis
= cpst_ResearchDevelopmentAndTestingOfMoreEfficientMicroturbineMember