UNAUDITED CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
UNAUDITED CONSOLIDATED STATEMENTS OF INCOME [Abstract]
Revenue	$ 123,254	$ 100,369
Cost of goods sold	61,749	50,174
Gross profit	61,505	50,195
Operating expenses:
Research, development and technical	13,396	14,828
Selling and marketing	7,552	6,749
General and administrative	12,496	14,263
Total operating expenses	33,444	35,840
Operating income	28,061	14,355
Interest expense	1,150	1,167
Other income, net	996	190
Income before income taxes	27,907	13,378
Provision for income taxes	5,676	2,069
Net income	$ 22,231	$ 11,309
Basic earnings per share (in dollars per share)	$ 0.90	$ 0.46
Weighted average basic shares outstanding (in shares)	24,582,688	24,141,726
Diluted earnings per share (in dollars per share)	$ 0.88	$ 0.46
Weighted average diluted shares outstanding (in shares)	25,072,165	24,548,765
Dividends per share (in dollars per share)	$ 0.18	$ 0