Revenue Recognition (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Operating income (loss)	$ (29,934)	$ (6,541)	$ (36,417)	$ (7,107)
Net income (loss) from continuing operations	$ (52,430)	$ (9,430)	$ (68,431)	$ (20,044)
Diluted earnings per share attributable to Cubic (in dollars per share)	$ (1.25)	$ (0.30)	$ (1.91)	$ (0.54)
ASU 2014-09 | Adjustments | ASC 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Operating income (loss)	$ (5,155)	$ (817)	$ (11,312)	$ 308
Net income (loss) from continuing operations	$ (5,522)	$ (503)	$ (11,304)	$ 292
Diluted earnings per share attributable to Cubic (in dollars per share)	$ (0.18)	$ (0.02)	$ (0.36)	$ 0.01