Segment Information - Business segment financial data (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) item	Jun. 30, 2016 USD ($)
Revenue recognition
Number of Operating Segments | item			3
Sales	$ 361,869	$ 375,240	$ 1,040,255	$ 1,055,077
Operating income (Loss)	(1,697)	13,893	(7,870)	(3,270)
Depreciation and amortization	12,418	12,966	38,154	31,943
Transportation Systems
Revenue recognition
Sales	136,400	156,000	407,900	430,500
Operating income (Loss)	(900)	20,500	16,600	43,900
Depreciation and amortization	2,400	1,200	6,800	5,400
Defense Systems
Revenue recognition
Sales	129,800	119,000	350,700	331,300
Operating income (Loss)	8,900	900	4,000	(23,700)
Depreciation and amortization	7,700	8,700	24,200	19,700
Cubic Global Defense Services
Revenue recognition
Sales	95,700	100,200	281,700	293,300
Operating income (Loss)	3,200	4,800	4,800	9,300
Depreciation and amortization	700	1,800	2,400	4,800
Corporate and other
Revenue recognition
Depreciation and amortization	1,700	1,300	4,800	2,000
Unallocated corporate expenses and other
Revenue recognition
Operating income (Loss)	$ (12,900)	$ (12,300)	$ (33,300)	$ (32,800)