Acquisitions and Divestitures - CGD Services - Assets and liabilities of discontinued (Details) - Discontinued operations held-for-sale - Cubic Global Defense Services - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2018	Sep. 30, 2017
Assets and liabilities
Accounts receivable - net	$ 76,515	$ 74,710
Other current assets	1,222	1,190
Property and equipment, net	367	466
Goodwill	94,350	94,350
Purchased intangibles, net	7,140	8,637
Other noncurrent assets	(3,616)	(5,179)
Total assets	175,978	174,174
Accounts payable and other liabilities	44,810	36,862
Net assets	$ 131,168	$ 137,312
Period for post closing support services from close date	7 years
Minimum
Assets and liabilities
Period for anticipated transaction to be completed	30 days
Maximum
Assets and liabilities
Period for anticipated transaction to be completed	60 days