Implementation of the New Revenue Recognition Standard - Effect on Statement of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Net sales:
Net sales	$ 337,339	$ 278,586	$ 642,598	$ 526,977
Costs and expenses:
Selling, general and administrative expenses	66,195	63,773	129,181	125,453
Research and development	13,754	14,202	25,766	26,179
Amortization of purchased intangibles	12,395	6,484	22,960	13,835
Restructuring costs	1,757	256	3,749	1,751
Total costs and expenses	343,880	280,265	649,705	540,558
Operating loss	(6,541)	(1,679)	(7,107)	(13,581)
Other income (expenses):
Interest and dividend income	1,413	625	2,647	1,107
Interest expense	(4,531)	(2,911)	(8,563)	(5,585)
Other income (expense), net	(3,602)	2,028	(8,355)	1,950
Loss from continuing operations before income taxes	(13,261)	(1,937)	(21,378)	(16,109)
Income tax (benefit) provision	(3,831)	1,409	(1,334)	(1,328)
Net income (loss) from continuing operations	(9,430)	(3,346)	(20,044)	(14,781)
Net loss from discontinued operations	(1,339)	1,335	(1,339)	2,984
Net loss	(10,769)	(2,011)	(21,383)	(11,797)
Less noncontrolling interest in loss of VIE	(1,377)		(5,404)
Net loss attributable to Cubic	(9,392)	(2,011)	(15,979)	(11,797)
Amounts attributable to Cubic:
Net loss from continuing operations	(8,053)	(3,346)	(14,640)	(14,781)
Net loss from discontinued operations	(1,339)	1,335	(1,339)	2,984
Net loss attributable to Cubic	$ (9,392)	$ (2,011)	$ (15,979)	$ (11,797)
Basic
Basic earnings per share attributable to Cubic (in dollars per share)	$ (0.30)	$ (0.07)	$ (0.54)	$ (0.43)
Diluted
Diluted earnings per share attributable to Cubic (in dollars per share)	$ (0.30)	$ (0.07)	$ (0.54)	$ (0.43)
ASC 605 | ASU 2014-09
Net sales:
Net sales	$ 309,635		$ 586,459
Costs and expenses:
Selling, general and administrative expenses	66,295		129,118
Research and development	13,754		25,766
Amortization of purchased intangibles	12,395		22,960
Restructuring costs	1,757		3,749
Total costs and expenses	321,569		602,290
Operating loss	(11,934)		(15,831)
Other income (expenses):
Interest and dividend income	74		130
Interest expense	(4,531)		(8,563)
Other income (expense), net	(3,602)		(8,355)
Loss from continuing operations before income taxes	(19,993)		(32,619)
Income tax (benefit) provision	(4,053)		(1,580)
Net income (loss) from continuing operations	(15,940)		(31,039)
Net loss from discontinued operations	(1,339)		(1,339)
Net loss	(17,279)		(32,378)
Less noncontrolling interest in loss of VIE	(3,885)		(9,866)
Net loss attributable to Cubic	(13,394)		(22,512)
Amounts attributable to Cubic:
Net loss from continuing operations	(12,055)		(21,173)
Net loss from discontinued operations	(1,339)		(1,339)
Net loss attributable to Cubic	$ (13,394)		$ (22,512)
Basic
Basic earnings per share attributable to Cubic (in dollars per share)	$ (0.43)		$ (0.75)
Diluted
Diluted earnings per share attributable to Cubic (in dollars per share)	$ (0.43)		$ (0.75)
ASC 606 | ASU 2014-09
Net sales:
Net sales	$ 27,704		$ 56,139
Costs and expenses:
Selling, general and administrative expenses	(100)		63
Total costs and expenses	22,311		47,415
Operating loss	5,393		8,724
Other income (expenses):
Interest and dividend income	1,339		2,517
Loss from continuing operations before income taxes	6,732		11,241
Income tax (benefit) provision	222		246
Net income (loss) from continuing operations	6,510		10,995
Net loss	6,510		10,995
Less noncontrolling interest in loss of VIE	2,508		4,462
Net loss attributable to Cubic	4,002		6,533
Amounts attributable to Cubic:
Net loss from continuing operations	4,002		6,533
Net loss attributable to Cubic	$ 4,002		$ 6,533
Basic
Basic earnings per share attributable to Cubic (in dollars per share)	$ 0.13		$ 0.22
Diluted
Diluted earnings per share attributable to Cubic (in dollars per share)	$ 0.13		$ 0.22
Products
Net sales:
Net sales	$ 222,744	$ 157,445	$ 404,997	$ 289,188
Costs and expenses:
Costs	167,567	117,093	293,052	208,666
Products | ASC 605 | ASU 2014-09
Net sales:
Net sales	195,588		348,150
Costs and expenses:
Costs	145,156		245,700
Products | ASC 606 | ASU 2014-09
Net sales:
Net sales	27,156		56,847
Costs and expenses:
Costs	22,411		47,352
Services
Net sales:
Net sales	114,595	121,141	237,601	237,789
Costs and expenses:
Costs	82,212	$ 78,457	174,997	$ 164,674
Services | ASC 605 | ASU 2014-09
Net sales:
Net sales	114,047		238,309
Costs and expenses:
Costs	82,212		174,997
Services | ASC 606 | ASU 2014-09
Net sales:
Net sales	$ 548		$ (708)