Fair Value Measurements (Marketable Equity and Cash Equivalents (Classified as Available-for-sale) and Cost Method Investments) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 38,902	$ 43,112
Gross Unrealized Holding Gains	5,949	10,218
Gross Unrealized Holding Losses	0	0
Fair Value	44,851	53,330
Money market instruments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	19,319	19,318
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Fair Value	19,319	19,318
Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	14,160	15,595
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Fair Value	14,160	15,595
Cash and Cash Equivalents
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	31,485	31,772
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Fair Value	31,485	31,772
Short-term Investments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,417	11,340
Gross Unrealized Holding Gains	5,949	10,218
Gross Unrealized Holding Losses	0	0
Fair Value	13,366	21,558
Semiconductor Manufacturing International Corp. | Available-for-sale Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,099	1,099
Gross Unrealized Holding Gains	1,252	694
Gross Unrealized Holding Losses	0	0
Fair Value	2,351	1,793
Nanya Technology Corporation | Available-for-sale Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,324	7,100
Gross Unrealized Holding Gains	4,697	9,524
Gross Unrealized Holding Losses	0	0
Fair Value	$ 9,021	$ 16,624