Variable Interest Entities - Net assets and liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
ASSETS
Restricted cash	$ 27,400	$ 8,400
Total assets	1,304,883	1,336,285	$ 1,504,700
LIABILITIES AND SHAREHOLDERS' EQUITY
Long-term debt	199,793	199,761
Total Cubic equity	700,121	689,631
Total liabilities and shareholders' equity	1,304,883	$ 1,336,285
VIE
ASSETS
Cash	374
Restricted cash	10,000
Long-term capitalized contract costs	1,258
Other noncurrent assets	810
Total assets	12,442
LIABILITIES AND SHAREHOLDERS' EQUITY
Trade accounts payable	165
Other noncurrent liabilities	13
Long-term debt	9,056
Total liabilities	9,234
Total Cubic equity	(304)
Noncontrolling interests	24,348
Total liabilities and shareholders' equity	33,278
VIE | Consolidation Eliminations
ASSETS
Total assets	$ (20,800)