Available For Sale Marketable Debt Securities (Summary Of Contractual Maturities Of Available For Sale Debt Securities) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Available For Sale Marketable Debt Securities [Abstract]
Less than one year, Cost	$ 13,660
Less than one year, Estimated Fair Value	13,679
Due between 1-2 years, Cost	8,319
Due between 1-2 years, Estimated Fair Value	8,363
Due between 2-5 years, Cost	7,566
Due between 2-5 years, Estimated Fair Value	7,588
Total, Cost	29,545
Total, Estimated Fair Value	$ 29,630	$ 25,709

This item represents the total of all debt securities grouped by maturity dates, at cost, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments, as defined), and fair value hedge accounting adjustments, if any, which are classified neither as held-to-maturity nor trading securities.

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This item represents debt securities, at cost, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments, as defined), and fair value hedge accounting adjustments, if any, which are expected to mature within one year of the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

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- Definition

This item represents the fair value of debt securities which are expected to mature within one year of the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

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- Definition

Total of debt securities categorized neither as held-to-maturity nor trading which are intended be sold or mature within one year from the balance sheet date or the normal operating cycle, whichever is longer.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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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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Reference 8: http://www.xbrl.org/2003/role/presentationRef

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