Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Nov. 30, 2021	Mar. 31, 2021
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	000-31157
Entity Registrant Name	INNOVATIVE SOLUTIONS AND SUPPORT, INC.
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Public Float			$ 83.4
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Amendment Flag	false
Current Fiscal Year End Date	--09-30
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		17,246,372
Entity Central Index Key	0000836690
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock par value $.001 per share
Security Exchange Name	NASDAQ
Entity Tax Identification Number	23-2507402
Entity Address, Address Line One	720 Pennsylvania Drive
Entity Incorporation, State or Country Code	PA
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
Trading Symbol	ISSC