Revenue Recognition (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Operating income (loss)	$ (25,555)	$ (29,934)	$ (24,258)	$ (36,417)
Net income (loss) from continuing operations	(19,240)	(52,430)	(26,518)	(68,431)
Net income (loss) from continuing operations attributable to Cubic	$ (36,017)	$ (39,252)	$ (49,012)	$ (59,243)
Diluted income (loss) per share attributable to Cubic	$ (1.14)	$ (1.25)	$ (1.55)	$ (1.91)
ASU 2014-09 | ASC 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Operating income (loss)	$ 222	$ (5,155)	$ 606	$ (11,312)
Net income (loss) from continuing operations	402	(5,522)	644	(11,304)
Net income (loss) from continuing operations attributable to Cubic	$ 263	$ (5,522)	$ 483	$ (11,304)
Diluted income (loss) per share attributable to Cubic	$ 0.01	$ (0.18)	$ 0.02	$ (0.36)