Condensed Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Net sales	$ 77,788	$ 64,781	$ 229,178	$ 193,450
Cost of sales	51,741	43,444	153,651	128,794
Gross profit	26,047	21,337	75,527	64,656
Operating expenses:
Research and development	10,583	6,749	30,914	20,856
Selling, general and administrative	10,829	9,392	32,648	28,307
Total operating expenses	21,412	16,141	63,562	49,163
Operating income	4,635	5,196	11,965	15,493
Interest and other income (expense), net	546	405	1,329	424
Gain on sale of investments	7,280	0	9,339	0
Income before income taxes	12,461	5,601	22,633	15,917
Provision for income taxes	5,215	2,454	9,619	5,404
Consolidated net income	7,246	3,147	13,014	10,513
Net (income) loss attributable to noncontrolling interests	(182)	(10)	(164)	15
Net income attributable to ISSI	$ 7,064	$ 3,137	$ 12,850	$ 10,528
Basic net income per share (in dollars per share)	$ 0.25	$ 0.11	$ 0.46	$ 0.39
Shares used in basic per share calculation (in shares)	28,293	27,316	27,988	27,002
Diluted net income per share (in dollars per share)	$ 0.24	$ 0.11	$ 0.44	$ 0.37
Shares used in diluted per share calculation	29,755	29,069	29,427	28,801