Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Jan. 08, 2024	Mar. 31, 2023
Cover
Document Type	10-K
Document Annual Report	true
Document Period End Date	Sep. 30, 2023
Document Transition Report	false
Entity File Number	001-41503
Entity Registrant Name	INNOVATIVE SOLUTIONS AND SUPPORT, INC.
Entity Incorporation, State or Country Code	PA
Entity Tax Identification Number	23-2507402
Entity Address, Address Line One	720 Pennsylvania Drive
Entity Address, City or Town	Exton
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	19341
City Area Code	610
Local Phone Number	646-9800
Title of 12(b) Security	Common Stock par value $.001 per share
Trading Symbol	ISSC
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 95.2
Entity Common Stock, Shares Outstanding		17,453,733
Entity Central Index Key	0000836690
Current Fiscal Year End Date	--09-30
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Amendment Flag	false
Auditor Name	GRANT THORNTON LLP
Auditor Firm ID	248
Auditor Location	Philadelphia, Pennsylvania