Segment Information - Business Segment Financial Data (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Segment Information
Sales	$ 328,839	$ 305,259
Operating income (loss)	(6,483)	(566)
Depreciation and amortization	16,950	16,011
Cubic Transportation Systems
Segment Information
Sales	188,600	181,800
Operating income (loss)	14,300	11,000
Depreciation and amortization	7,100	7,700
Cubic Mission Solutions
Segment Information
Sales	58,700	46,400
Operating income (loss)	(14,900)	(4,900)
Depreciation and amortization	7,500	5,400
Cubic Global Defense Systems
Segment Information
Sales	81,500	77,100
Operating income (loss)	6,300	2,900
Depreciation and amortization	1,700	2,200
Corporate
Segment Information
Depreciation and amortization	700	700
Unallocated corporate expenses and other
Segment Information
Operating income (loss)	$ (12,200)	$ (9,600)