Quarterly report pursuant to Section 13 or 15(d)

Other Current Liabilities (Details)

v2.4.1.9
Other Current Liabilities (Details) (USD $)
1 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2007
kW
Dec. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Dec. 31, 2014
Dec. 31, 2013
Mar. 31, 2014
UTCP              
Other Current Liabilities              
Capacity of microturbine (in kW) 200cpst_CapacityOfMicroturbine
/ dei_LegalEntityAxis
= cpst_UTCPowerCorporationMember
           
Cash contribution $ 12,000,000cpst_ResearchAndDevelopmentArrangementCashContributionByOtherParty
/ dei_LegalEntityAxis
= cpst_UTCPowerCorporationMember
           
In-kind services contribution 800,000cpst_ResearchAndDevelopmentArrangementInKindContributionByOtherParty
/ dei_LegalEntityAxis
= cpst_UTCPowerCorporationMember
           
Royalty payable (as a percent) 10.00%cpst_ResearchAndDevelopmentArrangementRoyaltyPayableAsPercentageOfSalesPrice
/ dei_LegalEntityAxis
= cpst_UTCPowerCorporationMember
           
Royalty payable after recovery of cash and in-kind services (as a percent) 5.00%cpst_ResearchAndDevelopmentArrangementRoyaltyPayableAsPercentageOfSalesPriceAfterRecoveryOfContributionsByOtherParty
/ dei_LegalEntityAxis
= cpst_UTCPowerCorporationMember
           
Carrier              
Other Current Liabilities              
Reduction in fixed rate royalty (as a percent)       50.00%cpst_ResearchAndDevelopmentArrangementPercentageOfReductionInFixedRateAfterRepaymentOfContributionsByOtherParty
/ dei_LegalEntityAxis
= cpst_CarrierCorporationMember
     
Royalty Revenue   400,000us-gaap_RoyaltyRevenue
/ dei_LegalEntityAxis
= cpst_CarrierCorporationMember
600,000us-gaap_RoyaltyRevenue
/ dei_LegalEntityAxis
= cpst_CarrierCorporationMember
  1,200,000us-gaap_RoyaltyRevenue
/ dei_LegalEntityAxis
= cpst_CarrierCorporationMember
2,200,000us-gaap_RoyaltyRevenue
/ dei_LegalEntityAxis
= cpst_CarrierCorporationMember
 
Unpaid earned royalties         $ 400,000cpst_RoyaltyPayable
/ dei_LegalEntityAxis
= cpst_CarrierCorporationMember
  $ 600,000cpst_RoyaltyPayable
/ dei_LegalEntityAxis
= cpst_CarrierCorporationMember