CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
CONSOLIDATED STATEMENTS OF INCOME [Abstract]
Revenue	$ 100,364	$ 99,236	$ 206,897	$ 201,358
Cost of goods sold	52,019	53,442	108,513	106,285
Gross profit	48,345	45,794	98,384	95,073
Operating expenses:
Research, development and technical	15,073	14,071	30,389	27,826
Selling and marketing	7,046	7,434	14,155	14,770
General and administrative	12,287	15,177	23,241	28,078
Total operating expenses	34,406	36,682	67,785	70,674
Operating income	13,939	9,112	30,599	24,399
Interest expense	872	354	1,825	393
Other income (expense), net	463	97	1,317	201
Income before income taxes	13,530	8,855	30,091	24,207
Provision for income taxes	4,110	3,325	10,968	8,262
Net income	$ 9,420	$ 5,530	$ 19,123	$ 15,945
Basic earnings per share	$ 0.41	$ 0.24	$ 0.84	$ 0.70
Weighted average basic shares outstanding	22,974	22,768	22,914	22,624
Diluted earnings per share	$ 0.40	$ 0.23	$ 0.81	$ 0.68
Weighted average diluted shares outstanding	23,871	23,780	23,755	23,378
Dividends per share	$ 0	$ 15.00	$ 0	$ 15.00