Per Share Data (Calculation of Basic and Diluted EPS) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended												12 Months Ended
	Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012	Sep. 30, 2012		Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Numerator for basic and diluted net income (loss) per share:
Net income (loss)	$ 4,698	[1]	$ 7,064	[2]	$ 3,287	[3]	$ 2,499	$ (13,246)	[4]	$ 3,137	$ 3,601	$ 3,790	$ 17,548	$ (2,718)	$ 55,957
Denominator for basic net income (loss) per share:
Weighted average common shares outstanding (in shares)													28,223	27,120	26,568
Dilutive stock options and awards (in shares)													1,471	0	1,740
Denominator for diluted net income (loss) per share (in shares)													29,694	27,120	28,308
Basic net income (loss) per share (in dollars per share)	$ 0.16		$ 0.25		$ 0.12		$ 0.09	$ (0.48)		$ 0.11	$ 0.13	$ 0.14	$ 0.62	$ (0.10)	$ 2.11
Diluted net income (loss) per share (in dollars per share)	$ 0.15		$ 0.24		$ 0.11		$ 0.09	$ (0.48)		$ 0.11	$ 0.12	$ 0.13	$ 0.59	$ (0.10)	$ 1.98

[1] In the September 2013 quarter, the Company realized a gain of $2.9 million from the sale of a portion of its Nanya shares.

[2] In the June 2013 quarter, the Company realized a gain from the sale of investments of $7.3 million including $7.0 million from the sale of a portion of its Nanya shares.

[3] In the March 2013 quarter, the Company realized a gain of $2.1 million from the sale of a portion of its Nanya shares.

[4] In the September 2012 quarter, the Company recorded a charge of approximately $14.3 million for the impairment of certain tangible and intangible assets related to the acquisition of Si En and a charge of approximately $2.3 million to write-down its investment in SMIC due to the decline in fair market value being considered other than temporary.