Cash, Cash Equivalents And Marketable Securities (Summary Of Cash, Cash Equivalents, And Marketable Securities) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Cash, Cash Equivalents And Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	$ 88,960	$ 139,806
Available-for-sale securities, Gross Unrealized Gains	79	62
Available-for-sale securities, Gross Unrealized Losses	(8)	(75)
Available-for-sale securities	89,031	139,793
Total available-for-sale securities, Amortized Cost	75,439	115,763
Total available-for-sale securities, Gross Unrealized Gains	79	62
Total available-for-sale securities, Gross Unrealized Losses	(8)	(75)
Total available-for-sale securities	75,510	115,750
Cash and Cash Equivalents [Member]
Cash, Cash Equivalents And Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	13,521	24,043
Available-for-sale securities	13,521	24,043
Corporate Debt Securities [Member] \| Maturing Within One Year [Member]
Cash, Cash Equivalents And Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	35,512	49,717
Available-for-sale securities, Gross Unrealized Gains	33	10
Available-for-sale securities, Gross Unrealized Losses	(5)	(9)
Available-for-sale securities	35,540	49,718
Corporate Debt Securities [Member] \| Maturing Between One And Two Years [Member]
Cash, Cash Equivalents And Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	4,934	17,767
Available-for-sale securities, Gross Unrealized Gains	14	7
Available-for-sale securities, Gross Unrealized Losses		(62)
Available-for-sale securities	4,948	17,712
U.S. Government Agency Debt Securities [Member] \| Maturing Within One Year [Member]
Cash, Cash Equivalents And Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	19,815	5,503
Available-for-sale securities, Gross Unrealized Gains	21	2
Available-for-sale securities	19,836	5,505
U.S. Government Agency Debt Securities [Member] \| Maturing Between One And Two Years [Member]
Cash, Cash Equivalents And Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	5,505	35,906
Available-for-sale securities, Gross Unrealized Gains	10	30
Available-for-sale securities, Gross Unrealized Losses		(4)
Available-for-sale securities	5,515	35,932
U.S. Treasury Securities [Member] \| Maturing Within One Year [Member]
Cash, Cash Equivalents And Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	3,314	6,870
Available-for-sale securities, Gross Unrealized Gains	1	13
Available-for-sale securities	3,315	6,883
U.S. Treasury Securities [Member] \| Maturing Between One And Two Years [Member]
Cash, Cash Equivalents And Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	6,359
Available-for-sale securities, Gross Unrealized Losses	(3)
Available-for-sale securities	6,356
Cash [Member] \| Cash and Cash Equivalents [Member]
Cash, Cash Equivalents And Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	7,640	5,629
Available-for-sale securities	7,640	5,629
Money Market Funds [Member] \| Cash and Cash Equivalents [Member]
Cash, Cash Equivalents And Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	882	12,467
Available-for-sale securities	882	12,467
Corporate Debt Securities [Member] \| Cash and Cash Equivalents [Member]
Cash, Cash Equivalents And Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	4,999	5,947
Available-for-sale securities	$ 4,999	$ 5,947

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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