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Summary of Significant Accounting Policies (Details 3) (USD $)
In Millions, unless otherwise specified
 3 Months Ended 12 Months Ended 3 Months Ended
Dec. 31, 2014
item
Sep. 30, 2014
Dec. 31, 2013
item
Concentration of Credit Risk      
Number of banks for maintenance of cash balances 2issc_NumberOfBanks    
Allowance for doubtful accounts $ 3.6issc_ProvisionForLossOnUnbilledReceivables $ 3.7issc_ProvisionForLossOnUnbilledReceivables  
Net sales | Major Customers      
Concentrations      
Number of major customers 3issc_NumberOfMajorCustomers
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= issc_RevenuesNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember		   4issc_NumberOfMajorCustomers
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= issc_RevenuesNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
Net sales | Major Customers | Pilatus      
Concentrations      
Sales percentage 25.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= issc_RevenuesNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= issc_PilatusAircraftLimitedMember		   13.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= issc_RevenuesNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= issc_PilatusAircraftLimitedMember
Net sales | Major Customers | DoD      
Concentrations      
Sales percentage 23.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= issc_RevenuesNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= issc_USDepartmentOfDefenseMember		   22.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= issc_RevenuesNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= issc_USDepartmentOfDefenseMember
Net sales | Major Customers | Eclipse      
Concentrations      
Sales percentage 11.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= issc_RevenuesNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= issc_EclipseAerospaceIncMember		   12.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= issc_RevenuesNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= issc_EclipseAerospaceIncMember
Net sales | Major Customers | FedEx      
Concentrations      
Sales percentage     11.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= issc_RevenuesNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= issc_FedExCorporationMember
Inventory | Major Suppliers      
Concentrations      
Number of major suppliers 2issc_NumberOfMajorSuppliers
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= issc_InventoryMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_SupplierConcentrationRiskMember		   1issc_NumberOfMajorSuppliers
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= issc_InventoryMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_SupplierConcentrationRiskMember