Fair Value Measurements (Assets and Liabilities that are Measured at Fair Value on a Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Sep. 30, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 44,851		$ 53,330
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	30,691		37,735
Money market instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	19,319		19,318
Money market instruments | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	19,319	[1]	19,318	[1]
Semiconductor Manufacturing International Corp. | Available-for-sale Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	2,351		1,793
Semiconductor Manufacturing International Corp. | Available-for-sale Securities | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	2,351	[2]	1,793	[2]
Nanya Technology Corporation | Available-for-sale Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	9,021		16,624
Nanya Technology Corporation | Available-for-sale Securities | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 9,021	[2]	$ 16,624	[2]

[1] Included in cash and cash equivalents

[2] Included in short-term investments