Variable Interest Entities - Net assets and liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Oct. 01, 2018	Sep. 30, 2018
ASSETS
Other current assets					$ 43,705	$ 43,705
Long-term contracts financing receivables						6,134
Other noncurrent assets	$ 70,396		$ 70,396
Total assets	1,814,885		1,814,885		1,321,130	1,304,883
LIABILITIES AND SHAREHOLDERS' EQUITY
Accrued compensation and other current liabilities					118,816	118,233
Shareholders' equity related to Cubic	945,813		945,813		719,955	700,121
Noncontrolling interest in consolidated VIE	19,769		19,769		28,730	24,075
Total liabilities and shareholders' equity	1,814,885		1,814,885		$ 1,321,130	1,304,883
Revenue	382,679	$ 296,212	1,025,277	$ 823,189
Operating income (loss)	34,725	10,290	27,618	(3,291)
Other income (expense), net	(8,714)	(3,831)	(17,069)	(1,881)
VIE
ASSETS
Cash	359		359			374
Restricted cash	9,967		9,967			10,000
Other current assets	53		53
Long-term capitalized contract costs						33,818
Long-term contracts financing receivables	90,233		90,233
Other noncurrent assets	1,266		1,266			810
Total assets	101,878		101,878			45,002
LIABILITIES AND SHAREHOLDERS' EQUITY
Trade accounts payable	88		88			165
Accrued compensation and other current liabilities	183		183
Other long term liabilities	16,897		16,897			13
Due to Cubic	19,460		19,460			11,724
Long-term debt	45,991		45,991			9,056
Total liabilities	82,619		82,619			20,958
Shareholders' equity related to Cubic	(510)		(510)			(304)
Noncontrolling interest in consolidated VIE	19,769		19,769			24,348
Total liabilities and shareholders' equity	101,878		101,878			$ 45,002
Revenue	3,233		7,519
Operating income (loss)	2,823		6,521
Other income (expense), net	(7,031)	$ (2,090)	(16,884)	$ (2,090)
Interest income	1,075		2,335
Interest Expense	$ (829)		$ (1,939)