Segment Information - Revenue Recognition Method (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue
Total sales	$ 305,259	$ 248,391
Point in time
Disaggregation of Revenue
Total sales	51,600
Over time
Disaggregation of Revenue
Total sales	253,700
Transportation Systems
Disaggregation of Revenue
Total sales	181,807	146,500
Transportation Systems | Point in time
Disaggregation of Revenue
Total sales	16,700
Transportation Systems | Over time
Disaggregation of Revenue
Total sales	165,100
Cubic Mission Solutions
Disaggregation of Revenue
Total sales	46,393	33,100
Cubic Mission Solutions | Point in time
Disaggregation of Revenue
Total sales	34,400
Cubic Mission Solutions | Over time
Disaggregation of Revenue
Total sales	12,000
Cubic Global Defense
Disaggregation of Revenue
Total sales	77,059	$ 68,800
Cubic Global Defense | Point in time
Disaggregation of Revenue
Total sales	500
Cubic Global Defense | Over time
Disaggregation of Revenue
Total sales	$ 76,600