Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies (Details 2)

v2.4.1.9
Summary of Significant Accounting Policies (Details 2) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Mar. 31, 2013
Geographic revenue information      
Total Revenue $ 115,461us-gaap_Revenues $ 133,105us-gaap_Revenues $ 127,557us-gaap_Revenues
United States      
Geographic revenue information      
Total Revenue 48,890us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= country_US
58,432us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= country_US
57,001us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= country_US
Mexico      
Geographic revenue information      
Total Revenue 14,468us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= country_MX
8,956us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= country_MX
22,581us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= country_MX
All other North America      
Geographic revenue information      
Total Revenue 331us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= cpst_AllOtherNorthAmericaMember
196us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= cpst_AllOtherNorthAmericaMember
4,370us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= cpst_AllOtherNorthAmericaMember
Total North America      
Geographic revenue information      
Total Revenue 63,689us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= us-gaap_NorthAmericaMember
67,584us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= us-gaap_NorthAmericaMember
83,952us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= us-gaap_NorthAmericaMember
Russia      
Geographic revenue information      
Total Revenue 12,978us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= country_RU
23,216us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= country_RU
13,827us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= country_RU
All other Europe      
Geographic revenue information      
Total Revenue 15,707us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= cpst_AllOtherEuropeMember
17,820us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= cpst_AllOtherEuropeMember
12,036us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= cpst_AllOtherEuropeMember
Total Europe      
Geographic revenue information      
Total Revenue 28,685us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= us-gaap_EuropeMember
41,036us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= us-gaap_EuropeMember
25,863us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= us-gaap_EuropeMember
Asia      
Geographic revenue information      
Total Revenue 9,257us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= us-gaap_AsiaMember
10,728us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= us-gaap_AsiaMember
8,473us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= us-gaap_AsiaMember
Australia      
Geographic revenue information      
Total Revenue 8,832us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= country_AU
5,275us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= country_AU
5,461us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= country_AU
All other      
Geographic revenue information      
Total Revenue $ 4,998us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= cpst_OtherCountriesMember
$ 8,482us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= cpst_OtherCountriesMember
$ 3,808us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= cpst_OtherCountriesMember