FINANCIAL INFORMATION BY INDUSTRY SEGMENT AND PRODUCT LINE, SEGMENT REPORTING INFORMATION BY PRODUCT TYPE (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) Segment	Jun. 30, 2015 USD ($)
FINANCIAL INFORMATION BY INDUSTRY SEGMENT AND PRODUCT LINE [Abstract]
Number of segments | Segment			1
Revenue from External Customer [Line Items]
Revenue	$ 108,152	$ 97,168	$ 307,765	$ 313,960
Tungsten Slurries [Member]
Revenue from External Customer [Line Items]
Revenue	46,559	43,533	134,856	132,335
Dielectric Slurries [Member]
Revenue from External Customer [Line Items]
Revenue	25,348	22,257	72,045	74,322
Other Metals Slurries [Member]
Revenue from External Customer [Line Items]
Revenue	16,048	16,927	46,586	55,155
Polishing Pads [Member]
Revenue from External Customer [Line Items]
Revenue	14,065	7,735	36,517	25,338
Data Storage Slurries [Member]
Revenue from External Customer [Line Items]
Revenue	1,750	2,977	5,684	11,277
Engineered Surface Finishes [Member]
Revenue from External Customer [Line Items]
Revenue	$ 4,382	$ 3,739	$ 12,077	$ 15,533