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Acquisitions and Divestitures - CGD Services - Income (loss) from discontinued operations (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2018	Apr. 18, 2018
Costs and expenses:
Net income (loss) from discontinued operations		$ (1,423)	$ 4,243	$ 14,531
Cubic Global Defense Services \| Disposed of by sale
Divestitures
Consideration from sale					$ 133,800	$ 135,000
Working capital settlement receivable			3,700
Increase (decrease) in working capital settlement receivable		(1,400)
Receivable for estimated earn-out amount due from purchaser		3,000
Receivable for estimated amount due from purchaser		0
Income (loss) from discontinued operations
Net sales			262,228	378,152
Costs and expenses:
Cost of sales			235,279	342,819
Selling, general and administrative expenses			11,365	17,487
Amortization of purchased intangibles			1,373	2,752
Restructuring costs			7	208
Other income			(15)	(46)
Earnings from discontinued operations before income taxes			14,219	14,932
Net (gain) loss on sale	$ 6,900	1,423	6,131
Income tax (benefit) provision			3,845	401
Net income (loss) from discontinued operations		$ (1,423)	$ 4,243	$ 14,531