Fair Value Measurements (Available-For-Sale Securities) (Details) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Available-for-sale securities, Amortized Cost	$ 206,614	$ 173,682
Available-for-sale securities, Gross Unrealized Gains		613
Available-for-sale securities, Gross Unrealized (Losses)	(3,159)	(1,468)
Available-for-sale securities, Fair Value	203,455	172,827
Total Included In Cash And Cash Equivalents [Member]
Available-for-sale securities, Amortized Cost	111,247	149,318
Available-for-sale securities, Fair Value	111,247	149,318
Total Other Short-Term Available-For-Sale Securities [Member]
Available-for-sale securities, Amortized Cost	71,003
Available-for-sale securities, Fair Value	71,003
Long-Term Available-For-Sale Securities [Member]
Available-for-sale securities, Amortized Cost	24,364	24,364
Available-for-sale securities, Gross Unrealized Gains		613
Available-for-sale securities, Gross Unrealized (Losses)	(3,159)	(1,468)
Available-for-sale securities, Fair Value	21,205	23,509
Money Market Funds [Member]
Available-for-sale securities, Amortized Cost	111,247	149,318
Available-for-sale securities, Fair Value	111,247	149,318
Commercial Paper [Member]
Available-for-sale securities, Amortized Cost	71,003
Available-for-sale securities, Fair Value	71,003
Auction-Rate Securities [Member]
Available-for-sale securities, Amortized Cost	18,800	18,800
Available-for-sale securities, Gross Unrealized (Losses)	(1,295)	(1,468)
Available-for-sale securities, Fair Value	17,505	17,332
Equity Securities [Member]
Available-for-sale securities, Amortized Cost	5,564	5,564
Available-for-sale securities, Gross Unrealized Gains		613
Available-for-sale securities, Gross Unrealized (Losses)	(1,864)
Available-for-sale securities, Fair Value	$ 3,700	$ 6,177

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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