Fair Value Measurements (Marketable Equity and Cash Equivalents (Classified as Available-for-sale) and Cost Method Investments) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Sep. 30, 2012
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 49,376	$ 70,305
Gross Unrealized Holding Gains	14,320	0
Gross Unrealized Holding Losses	0	(1,835)
Fair Value	63,696	68,470
Money market instruments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	19,313	34,317
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Fair Value	19,313	34,317
Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	15,288	18,302
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Fair Value	15,288	18,302
Cash and Cash Equivalents and Restricted Cash
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	29,333	47,177
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Fair Value	29,333	47,177
Short-term Investments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	20,043	23,128
Gross Unrealized Holding Gains	14,320	0
Gross Unrealized Holding Losses	0	(1,835)
Fair Value	34,363	21,293
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	672	0
Gross Unrealized Holding Losses	0	0
Fair Value	1,771	1,099
Nanya Technology Corporation \| Available-for-sale Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	13,676	16,587
Gross Unrealized Holding Gains	13,648	0
Gross Unrealized Holding Losses	0	(1,835)
Fair Value	$ 27,324	$ 14,752

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

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