Implementation of the New Revenue Recognition Standard - Effect on Statement of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								9 Months Ended	12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Net sales:
Net sales	$ 471,198	$ 382,679	$ 337,339	$ 305,259	$ 379,709	$ 296,212	$ 278,586	$ 248,391		$ 1,496,475	$ 1,202,898	$ 1,107,709
Costs and expenses:
Selling, general and administrative expenses										270,064	258,644	240,196
Research and development										50,132	52,398	52,652
Amortization of purchased intangibles										42,106	27,064	30,245
(Gain) loss on sale of property, plant and equipment									$ (32,500)	(32,510)		405
Restructuring costs										15,386	5,018	2,260
Total costs and expenses										1,410,238	1,178,516	1,105,081
Operating income	58,619	34,725	(6,541)	(566)	27,673	10,290	(1,679)	(11,902)		86,237	24,382	2,628
Other income (expenses):
Interest and dividend income										6,519	1,615	953
Interest expense										(20,453)	(10,424)	(15,027)
Other income (expense), net										(19,957)	(687)	364
Income (loss) from continuing operations before income taxes										52,346	14,886	(11,082)
Income tax provision										11,040	7,093	14,658
Income (loss) from continuing operations										41,306	7,793	(25,740)
Net loss from discontinued operations										(1,423)	4,243	14,531
Net income (loss)										39,883	12,036	(11,209)
Less noncontrolling interest in loss of VIE										(9,811)	(274)
Net income (loss) attributable to Cubic	41,763	23,910	(9,392)	(6,587)	17,816	6,291	(2,011)	(9,786)		49,694	12,310	(11,209)
Amounts attributable to Cubic:
Net income from continuing operations										51,117	8,067	(25,740)
Net loss from discontinued operations										(1,423)	4,243	14,531
Net income (loss) attributable to Cubic	$ 41,763	$ 23,910	$ (9,392)	$ (6,587)	$ 17,816	$ 6,291	$ (2,011)	$ (9,786)		$ 49,694	$ 12,310	$ (11,209)
Net income (loss) per share:
Basic earnings per share attributable to Cubic (in dollars per share)	$ 1.39	$ 0.77	$ (0.30)	$ (0.23)	$ 0.65	$ 0.23	$ (0.07)	$ (0.36)		$ 1.63	$ 0.45	$ (0.41)
Diluted earnings per share attributable to Cubic (in dollars per share)	$ 1.38	$ 0.77	$ (0.30)	$ (0.23)	$ 0.65	$ 0.23	$ (0.07)	$ (0.36)		$ 1.62	$ 0.45	$ (0.41)
ASC 605 | ASU 2014-09
Net sales:
Net sales										$ 1,387,276
Costs and expenses:
Selling, general and administrative expenses										269,266
Research and development										50,132
Amortization of purchased intangibles										42,106
(Gain) loss on sale of property, plant and equipment										(32,510)
Restructuring costs										15,386
Total costs and expenses										1,315,924
Operating income										71,352
Other income (expenses):
Interest and dividend income										394
Interest expense										(20,453)
Other income (expense), net										(19,957)
Income (loss) from continuing operations before income taxes										31,336
Income tax provision										11,059
Income (loss) from continuing operations										20,277
Net loss from discontinued operations										(1,423)
Net income (loss)										18,854
Less noncontrolling interest in loss of VIE										(22,076)
Net income (loss) attributable to Cubic										40,930
Amounts attributable to Cubic:
Net income from continuing operations										42,353
Net loss from discontinued operations										(1,423)
Net income (loss) attributable to Cubic										$ 40,930
Net income (loss) per share:
Basic earnings per share attributable to Cubic (in dollars per share)										$ 1.34
Diluted earnings per share attributable to Cubic (in dollars per share)										$ 1.34
ASC 606 | ASU 2014-09
Net sales:
Net sales										$ 109,199
Costs and expenses:
Selling, general and administrative expenses										798
Total costs and expenses										94,314
Operating income										14,885
Other income (expenses):
Interest and dividend income										6,125
Income (loss) from continuing operations before income taxes										21,010
Income tax provision										(19)
Income (loss) from continuing operations										21,029
Net income (loss)										21,029
Less noncontrolling interest in loss of VIE										12,265
Net income (loss) attributable to Cubic										8,764
Amounts attributable to Cubic:
Net income from continuing operations										8,764
Net income (loss) attributable to Cubic										$ 8,764
Net income (loss) per share:
Basic earnings per share attributable to Cubic (in dollars per share)										$ 0.29
Diluted earnings per share attributable to Cubic (in dollars per share)										$ 0.29
Products
Net sales:
Net sales										$ 1,011,069	$ 704,941	$ 681,559
Costs and expenses:
Costs										732,137	472,698	473,670
Products | ASC 605 | ASU 2014-09
Net sales:
Net sales										902,913
Costs and expenses:
Costs										638,621
Products | ASC 606 | ASU 2014-09
Net sales:
Net sales										108,156
Costs and expenses:
Costs										93,516
Services
Net sales:
Net sales										485,406	497,957	426,150
Costs and expenses:
Costs										332,923	$ 362,694	$ 305,653
Services | ASC 605 | ASU 2014-09
Net sales:
Net sales										484,363
Costs and expenses:
Costs										332,923
Services | ASC 606 | ASU 2014-09
Net sales:
Net sales										$ 1,043