Short-Term Investments (Schedule Of Available For Sale Investments) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 109,732	$ 128,494
Gross unrealized gains	51	57
Gross unrealized losses	65	73
Fair value	109,718	128,478
US Treasury [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	25,003	48,351
Gross unrealized gains	1	14
Gross unrealized losses	21	3
Fair value	24,983	48,362
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	84,729	80,143
Gross unrealized gains	50	43
Gross unrealized losses	44	70
Fair value	84,735	80,116
Available For Sale Investments Maturities Less Than One Year [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	75,677	99,190
Gross unrealized gains	51	42
Gross unrealized losses	26	39
Fair value	75,702	99,193
Available For Sale Investments Maturities Longer Than One Year [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	34,055	29,304
Gross unrealized gains		15
Gross unrealized losses	39	34
Fair value	$ 34,016	$ 29,285

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.

+ References+ Details

For an unclassified balance sheet, total of debt securities categorized neither as held-to-maturity nor trading.

+ References

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

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-Name Statement of Financial Accounting Standard (FAS)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef

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+ Details

- 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.

+ References+ Details