Summary of Significant Accounting Policies - Revenue Recognition (Details)	12 Months Ended
Sep. 30, 2021
Revenue Recognition.
Percentage of revenue from products to customer	100.00%

The percentage of revenue from products transferred to customers at a point in time.

No definition available.

Name:	issc_RevenuePerformanceObligationSatisfiedAtPointInTimePercentageOfRevenue
Namespace Prefix:	issc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration