Acquisitions and Divestitures - CGD Services - Income (loss) from discontinued operations (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Apr. 18, 2018
Costs and expenses:
Discontinued operations income tax provision (benefit)				$ 1,200
Net income (loss) from discontinued operations		$ 1,335	$ (41,410)	2,984	$ (45,294)
Cubic Global Defense Services | Discontinued operations held-for-sale
Divestitures
Loss on sale of CGD Services	$ (6,900)
Estimated disposal costs	$ 4,200
Income (loss) from discontinued operations
Net sales		98,068	95,669	190,361	185,976
Costs and expenses:
Cost of sales		87,562	85,991	170,682	169,289
Selling, general and administrative expenses		3,876	4,712	7,543	9,282
Amortization of purchased intangibles		489	608	1,097	1,537
Restructuring costs		7	346	7	334
Other income		(8)	(10)	(13)	(33)
Earnings from discontinued operations before income taxes		6,142	4,022	11,045	5,567
Discontinued operations income tax provision (benefit)		(2,093)	45,432	1,161	50,861
Net loss upon classification of operations as held for sale		6,900		6,900
Net income (loss) from discontinued operations		$ 1,335	$ (41,410)	$ 2,984	$ (45,294)
Cubic Global Defense Services | Subsequent event | Discontinued operations held-for-sale
Divestitures
Sales price in the definitive agreement						$ 135,000
Cubic Global Defense Services | Subsequent event | Discontinued operations held-for-sale
Divestitures
Sales price in the definitive agreement						135,000
Additional cash payment to be received based on achievement of pre-determined earn-out conditions						$ 3,000