Segment Information - Sales by Deliverable Type (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue
Total sales	$ 305,259	$ 248,391
Products
Disaggregation of Revenue
Total sales	182,253	131,743
Services
Disaggregation of Revenue
Total sales	123,006	116,648
Transportation Systems
Disaggregation of Revenue
Total sales	181,807	146,500
Transportation Systems | Products
Disaggregation of Revenue
Total sales	92,000
Transportation Systems | Services
Disaggregation of Revenue
Total sales	89,800
Cubic Mission Solutions
Disaggregation of Revenue
Total sales	46,393	33,100
Cubic Mission Solutions | Products
Disaggregation of Revenue
Total sales	40,600
Cubic Mission Solutions | Services
Disaggregation of Revenue
Total sales	5,800
Cubic Global Defense
Disaggregation of Revenue
Total sales	77,059	$ 68,800
Cubic Global Defense | Products
Disaggregation of Revenue
Total sales	49,700
Cubic Global Defense | Services
Disaggregation of Revenue
Total sales	$ 27,400