Restructuring Costs - Restructuring Charges (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Restructuring plan
Restructuring costs	$ 1,575	$ 1,992
Unallocated corporate expenses and other
Restructuring plan
Restructuring costs	1,100	1,500
Cubic Transportation Systems
Restructuring plan
Restructuring costs	400	400
Cubic Global Defense Systems
Restructuring plan
Restructuring costs	$ 100	$ 100