Acquisitions - Goodwill and Pro forma information (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended		12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2017	Mar. 31, 2016	Sep. 30, 2016
Unaudited pro forma information
Net sales	$ 343,700		$ 369,100		$ 678,600	$ 703,200
Net income attributable to Cubic	500		$ 9,500		(2,700)	$ 3,800
Adjustments made for transaction expenses		$ 0		$ 0
Changes in the carrying amount of goodwill
Balance at the beginning of the period		406,946			406,946
Acquisitions					3,642
Foreign currency exchange rate changes					(1,497)
Balance at the end of the period	409,091				409,091		$ 406,946
Transportation Systems
Changes in the carrying amount of goodwill
Balance at the beginning of the period		49,630			49,630
Foreign currency exchange rate changes					(1,266)
Balance at the end of the period	48,364				48,364		$ 49,630
Transportation Systems | Minimum
Components of net goodwill
Estimated percentage of excess of fair value over carrying value							20.00%
Defense Systems
Changes in the carrying amount of goodwill
Balance at the beginning of the period		262,966			262,966
Acquisitions					3,642
Foreign currency exchange rate changes					(231)
Balance at the end of the period	266,377				266,377		$ 262,966
Defense Systems | Minimum
Components of net goodwill
Estimated percentage of excess of fair value over carrying value							20.00%
Cubic Global Defense Services
Changes in the carrying amount of goodwill
Balance at the beginning of the period		$ 94,350			94,350
Balance at the end of the period	$ 94,350				$ 94,350		$ 94,350
Cubic Global Defense Services | Minimum
Components of net goodwill
Estimated percentage of excess of fair value over carrying value							15.00%