Cash And Cash Equivalents And Investments (Summary Of Investments By Category) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010
Cash And Cash Equivalents And Investments [Line Items]
Total investments, Gross Unrealized Gains	$ 150	$ 329
Total investments, Gross Unrealized Losses	(196)	(9)
Total investments, Amortized Cost	61,652	135,430
Total investments, Fair Value	61,606	135,750
US Treasury Securities [Member]
Cash And Cash Equivalents And Investments [Line Items]
Available-for-sale securities, Amortized Cost	6,920	24,463
Available-for-sale securities, Fair Value	6,921	24,511
Available-for-sale securities, Gross Unrealized Gains	1	48
Available-for-sale securities, Gross Unrealized Losses
US Agency Securities [Member]
Cash And Cash Equivalents And Investments [Line Items]
Available-for-sale securities, Amortized Cost	5,526	35,331
Available-for-sale securities, Fair Value	5,551	35,387
Available-for-sale securities, Gross Unrealized Gains	25	61
Available-for-sale securities, Gross Unrealized Losses		(5)
Commercial Paper [Member]
Cash And Cash Equivalents And Investments [Line Items]
Available-for-sale securities, Amortized Cost		14,980
Available-for-sale securities, Fair Value		14,984
Available-for-sale securities, Gross Unrealized Gains		6
Available-for-sale securities, Gross Unrealized Losses		(2)
Corporate Notes/Bonds [Member]
Cash And Cash Equivalents And Investments [Line Items]
Available-for-sale securities, Amortized Cost	47,600	50,969
Available-for-sale securities, Fair Value	47,528	51,181
Available-for-sale securities, Gross Unrealized Gains	124	214
Available-for-sale securities, Gross Unrealized Losses	(196)	(2)
Certificates/Term Deposits [Member]
Cash And Cash Equivalents And Investments [Line Items]
Available-for-sale securities, Amortized Cost	1,606	9,687
Available-for-sale securities, Fair Value	1,606	9,687
Available-for-sale securities, Gross Unrealized Gains
Available-for-sale securities, Gross Unrealized Losses

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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- Definition

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