INCOME TAXES - Components of income (loss) and provision for income taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Components of income (loss) before income taxes
United States	$ (57,176)	$ (18,712)	$ (22,788)
Foreign	49,699	90,623	112,199
Income (loss) before income taxes	(7,477)	71,911	89,411
Current:
Federal	2,469	(2,433)	(8,049)
State	(231)	723	918
Foreign	8,249	20,266	25,705
Total current	10,487	18,556	18,574
Deferred:
Federal	(15,614)	24,112	1,296
State	(4,365)	5,710	(1,232)
Foreign	280	619	1,193
Total deferred	(19,699)	30,441	1,257
Provision for income taxes	$ (9,212)	$ 48,997	$ 19,831