INCOME TAXES, Effective tax rates (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Effective income tax rates as compared to the U.S. Federal income tax rate
U.S. Federal income tax rate (as a percent)	35.00%	35.00%	35.00%
Effect of foreign taxes (as a percent)	1.80%	(13.80%)	(3.20%)
State income taxes, net of federal tax benefit (as a percent)	0.60%	3.20%	0.80%
U.S. domestic production activities (as a percent)	(2.10%)	(10.40%)	(1.20%)
Other impact of foreign operations	(2.90%)	14.70%	4.50%
Other (as a percent)	(1.70%)	(1.60%)	0.60%
Effective income tax rate (as a percent)	30.70%	27.10%	36.50%
Accrued interest and penalties related to unrecognized tax benefits	$ 2,800	$ 6,800
Reconciliation of the change in gross unrecognized tax benefits
Unrecognized tax benefits at the beginning of the period	9,551	11,211
Gross decreases - tax positions in prior periods	(1)
Gross decreases - current period effect of tax positions	(170)	(1,173)
Gross increases - current period effect of tax positions	300	969
Expiration of statute of limitations for assessments	(4,907)	(679)
Settlements		(777)
Unrecognized tax benefits at the end of the period	4,773	9,551	$ 11,211
Unrecognized tax benefits related to discontinued operations	$ 3,700	$ 3,800