COMMITMENTS AND CONTINGENCIES (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Movement in standard product warranty accrual [Roll Forward]
Beginning balance	$ 384
Reserve for product warranty during the reporting period	867
Settlement of warranty	(892)
Ending balance	359	384
Lease commitments [Abstract]
Expiration of cancelable and noncancelable leases, maximum (in years)	6
Rent expense under operating leases	3,199	2,934	2,480
Initial present value of the minimum quarterly payments for the capital lease	9,776
Operating leases, future minimum payments due:
2013	2,830
2014	2,179
2015	1,116
2016	1,013
2017	785
Thereafter	520
Operating leases, total	8,443
Capital leases, future minimum payments due:
2013	2
2014	5
2015	5
2016	5
2017	4
Thereafter	0
Capita leases including interest portion	21
Amount related to interest	0
Capital leases, future minimum payments due, total	21
Purchase obligations [Abstract]
Percentage of volume forecast of fumed silica required to be purchased under purchase obligation, minimum (in hundredths)	90.00%
Number of months used for volume forecast of fumed silica to determine purchase obligations (in months)	six
Contractual commitments for fumed silica and fumed alumina under purchase obligations	$ 8,994