Segment Information - Business segment financial data (Details) $ in Thousands	3 Months Ended
	Dec. 31, 2017 USD ($) item	Dec. 31, 2016 USD ($)
Revenue recognition
Number of Operating Segments | item	3
Sales	$ 340,684	$ 334,677
Operating income (Loss)	(7,004)	(4,101)
Depreciation and amortization	13,109	13,444
Transportation Systems
Revenue recognition
Sales	146,500	131,900
Operating income (Loss)	9,900	9,700
Depreciation and amortization	3,200	2,400
Defense Systems
Revenue recognition
Sales	68,800	78,600
Operating income (Loss)	1,400	3,300
Depreciation and amortization	1,700	2,000
Cubic Mission Solutions
Revenue recognition
Sales	33,100	33,900
Operating income (Loss)	(8,900)	(3,800)
Depreciation and amortization	5,900	6,800
Cubic Global Defense Services
Revenue recognition
Sales	92,300	90,300
Operating income (Loss)	2,900	(400)
Depreciation and amortization	700	1,000
Corporate and other
Revenue recognition
Depreciation and amortization	1,600	1,200
Unallocated corporate expenses and other
Revenue recognition
Operating income (Loss)	$ (12,300)	$ (12,900)