CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
CONSOLIDATED STATEMENTS OF INCOME [Abstract]
Revenue	$ 97,168	$ 108,358	$ 313,960	$ 308,329
Cost of goods sold	48,609	56,632	153,751	162,364
Gross profit	48,559	51,726	160,209	145,965
Operating expenses:
Research, development and technical	14,773	15,368	44,922	44,303
Selling and marketing	5,804	6,489	19,220	19,667
General and administrative	12,830	11,380	38,877	33,182
Total operating expenses	33,407	33,237	103,019	97,152
Operating income	15,152	18,489	57,190	48,813
Interest expense	1,065	832	3,030	2,547
Other income (expense), net	(160)	(132)	565	588
Income before income taxes	13,927	17,525	54,725	46,854
Provision for income taxes	4,041	4,223	11,112	12,149
Net income	$ 9,886	$ 13,302	$ 43,613	$ 34,705
Basic earnings per share (in dollars per share)	$ 0.40	$ 0.55	$ 1.80	$ 1.45
Weighted average basic shares outstanding (in shares)	24,332,879	23,752,770	24,004,885	23,768,858
Diluted earnings per share (in dollars per share)	$ 0.39	$ 0.53	$ 1.75	$ 1.39
Weighted average diluted shares outstanding (in shares)	24,813,462	24,613,492	24,654,853	24,704,369