Marketable Securities (Summary Of Cash, Cash Equivalents, And Marketable Securities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Corporate Debt Securities [Member] \| Maturing Within One Year [Member]
Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	$ 21,662	$ 49,717
Available-for-sale securities, Gross Unrealized Gains	31	10
Available-for-sale securities, Gross Unrealized Losses		(9)
Available-for-sale securities, Fair Value	21,693	49,718
Corporate Debt Securities [Member] \| Maturing Between One And Two Years [Member]
Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	7,858	17,767
Available-for-sale securities, Gross Unrealized Gains	7	7
Available-for-sale securities, Gross Unrealized Losses	(2)	(62)
Available-for-sale securities, Fair Value	7,863	17,712
U.S. Government Agency Debt Securities [Member] \| Maturing Within One Year [Member]
Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	14,027	5,503
Available-for-sale securities, Gross Unrealized Gains	8	2
Available-for-sale securities, Fair Value	14,035	5,505
U.S. Government Agency Debt Securities [Member] \| Maturing Between One And Two Years [Member]
Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	3,208	35,906
Available-for-sale securities, Gross Unrealized Gains	8	30
Available-for-sale securities, Gross Unrealized Losses		(4)
Available-for-sale securities, Fair Value	3,216	35,932
U.S. Treasury Securities [Member] \| Maturing Within One Year [Member]
Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	2,008	6,870
Available-for-sale securities, Gross Unrealized Gains	1	13
Available-for-sale securities, Fair Value	2,009	6,883
Total Available-For-Sale Securities [Member]
Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	48,763
Available-for-sale securities, Gross Unrealized Gains	55
Available-for-sale securities, Gross Unrealized Losses	(2)
Available-for-sale securities, Fair Value	48,816
Total Available-For-Sale Securities [Member] \| Maturing Between One And Two Years [Member]
Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost		115,763
Available-for-sale securities, Gross Unrealized Gains		62
Available-for-sale securities, Gross Unrealized Losses		(75)
Available-for-sale securities, Fair Value		115,750
Total Cash, Cash Equivalents And Marketable Securities [Member]
Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	77,839	139,806
Available-for-sale securities, Gross Unrealized Gains	55	62
Available-for-sale securities, Gross Unrealized Losses	(2)	(75)
Available-for-sale securities, Fair Value	77,892	139,793
Cash [Member]
Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	11,769	5,629
Available-for-sale securities, Fair Value	11,769	5,629
Money Market Funds [Member]
Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	11,268	12,467
Available-for-sale securities, Fair Value	11,268	12,467
Corporate Debt Securities [Member]
Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	6,039	5,947
Available-for-sale securities, Fair Value	6,039	5,947
Total Cash and Cash Equivalents [Member]
Marketable Securities [Line Items]
Available-for-sale securities, Amortized Cost	29,076	24,043
Available-for-sale securities, Fair Value	$ 29,076	$ 24,043

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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