Fair Value Measurements (Amortized Cost And Estimated Fair Value Of Available-For-Sale Marketable Securities) (Details) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Amortized Cost [Member]
Schedule of Available-for-sale Securities [Line Items]
Equity securities	$ 166,460	$ 103,189
Debt securities	297,024	271,260
Total available-for-sale securities	463,484	374,449
Estimated Fair Value [Member]
Schedule of Available-for-sale Securities [Line Items]
Equity securities	155,266	105,304
Debt securities	294,410	274,029
Total available-for-sale securities	$ 449,676	$ 379,333

For an unclassified balance sheet, this item represents investments in debt and equity securities which are categorized neither as held-to-maturity nor trading.

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

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