Stockholders' Equity (Schedule of Accumulated Other Comprehensive Income) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Schedule of Available-for-sale Securities [Line Items]
Accumulated foreign currency translation adjustments	$ 1,051	$ 4,787
Accumulated net retirement plan transition asset (net of tax of $124 in 2014 and $148 in 2013)	8	47
Accumulated net retirement plan transition assets, tax	124	148
Accumulated net retirement plan actuarial losses (net of tax of $477 in 2014 and $470 in 2013)	(2,103)	(2,091)
Accumulated net retirement plan actuarial losses, tax	477	470
Total accumulated other comprehensive income (loss)	(1,044)	9,121
Estimated net prior service cost	0
Estimated actuarial loss	116
Estimated transition obligation	(59)
SMIC
Schedule of Available-for-sale Securities [Line Items]
Accumulated net unrealized gain on investment	0	419
Accumulated net unrealized gain on investment, tax	0	275
Nanya
Schedule of Available-for-sale Securities [Line Items]
Accumulated net unrealized gain on investment	0	5,959
Accumulated net unrealized gain on investment, tax	$ 0	$ 3,565