It represents information about percentage of dividend on ordinary income.

No definition available.

Name:	issc_PercentageOfDividendOnOrdinaryIncome
Namespace Prefix:	issc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

It represents information about percentage of dividend on return on capital.

+ References

No definition available.

+ Details

Name:	issc_PercentageOfDividendOnReturnOnCapital
Namespace Prefix:	issc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Aggregate dividends declared during the period for each share of common stock outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

+ Details

Name:	us-gaap_CommonStockDividendsPerShareDeclared
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of paid and unpaid common stock dividends declared with the form of settlement in cash.

+ References

+ Details

Name:	us-gaap_DividendsCommonStockCash
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

Name:	us-gaap_SubsequentEventLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Millions				12 Months Ended
	Dec. 10, 2020	Oct. 01, 2020	Sep. 04, 2020	Sep. 30, 2020
Subsequent Event
Cash dividends declared per share			$ 0.65
Aggregate amount of dividend payment				$ 11.2
Subsequent Event
Subsequent Event
Cash dividends declared per share	$ 0.50	$ 0.65
Aggregate amount of dividend payment	$ 8.6
Percentage of dividend on ordinary income		20.00%
Percentage of dividend on return on capital		80.00%