Fair Value Of Financial Instruments (Amortized Cost And Fair Value Of Marketable Securities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Fair Value Of Financial Instruments [Abstract]
Debt securities - maturity less than 1 year, Amortized Cost	$ 61,200	$ 469,318
Debt securities - maturity 1 to 5 years, Amortized Cost	20,365	120,078
Total, Amortized Cost	81,565	589,396
Debt securities - maturity less than 1 year, Estimated Fair Value	61,134	469,956
Debt securities - maturity 1 to 5 years, Estimated Fair Value	20,244	121,406
Total, Estimated Fair Value	$ 81,378	$ 591,362

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 after one year and through five years from the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

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This item represents the fair value of debt securities which are expected to mature after one year and through five years from 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 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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- Definition

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

This item represents the fair value of debt securities, categorized neither as held-to-maturity nor trading securities, which do not have a single maturity date and which the Company has decided to disclose separately, rather than allocating such cost over several maturity groupings.

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