Condensed Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Net sales	$ 64,781	$ 69,809	$ 193,450	$ 199,169
Cost of sales	43,444	46,639	128,794	132,599
Gross profit	21,337	23,170	64,656	66,570
Operating expenses:
Research and development	6,749	6,525	20,856	20,096
Selling, general and administrative	9,392	9,120	28,307	27,099
Total operating expenses	16,141	15,645	49,163	47,195
Operating income	5,196	7,525	15,493	19,375
Interest and other income, net	405	660	424	1,258
Gain on sale of investments	0	0	0	560
Income before income taxes	5,601	8,185	15,917	21,193
Provision for income taxes	2,454	90	5,404	126
Consolidated net income	3,147	8,095	10,513	21,067
Net loss (income) attributable to noncontrolling interests	(10)	(5)	15	16
Net income attributable to ISSI	$ 3,137	$ 8,090	$ 10,528	$ 21,083
Basic net income per share	$ 0.11	$ 0.30	$ 0.39	$ 0.79
Shares used in basic per share calculation	27,316	26,768	27,002	26,546
Diluted net income per share	$ 0.11	$ 0.28	$ 0.37	$ 0.74
Shares used in diluted per share calculation	29,069	28,551	28,801	28,322