Document and Entity Information - shares	3 Months Ended
	Dec. 31, 2020	Jan. 21, 2021
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2020
Entity File Number	001-08931
Entity Registrant Name	CUBIC CORP /DE/
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	95-1678055
Entity Address, Address Line One	9333 Balboa Avenue
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92123
City Area Code	858
Local Phone Number	277-6780
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		31,834,085
Current Fiscal Year End Date	--09-30
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Entity Central Index Key	0000026076
Amendment Flag	false
Common Stock
Document Information [Line Items]
Title of 12(b) Security	Common Stock, no par value
Trading Symbol	CUB
Security Exchange Name	NYSE
Preferred Stock Purchase Rights
Document Information [Line Items]
Title of 12(b) Security	Preferred Stock Purchase Rights
No Trading Symbol Flag	true
Security Exchange Name	NYSE