Quarterly report pursuant to Section 13 or 15(d)

Short-Term And Long-Term Investments And Restricted Deposits (Narrative) (Details)

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Short-Term And Long-Term Investments And Restricted Deposits (Narrative) (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 9 Months Ended
Sep. 30, 2012
positions
Sep. 30, 2011
Sep. 30, 2012
positions
Sep. 30, 2011
Investments, Debt and Equity Securities [Abstract]        
Percentage of investments in securities recorded at fair value that carry a rating by Moody's or S&P of AAA 38.00%   38.00%  
Percentage of investments in securities recorded at fair value that carry a rating by Moody's or S&P of AA- or higher 68.00%   68.00%  
Percentage of investments in securities recorded at fair value that carry a rating by Moody's or S&P of A- or higher 99.00%   99.00%  
Positions from which gross unrealized losses were generated 8   8  
Total positions 376   376  
Marketable Securities, Realized Gain (Loss), Excluding Other than Temporary Impairments $ 1,463 $ 106 $ 1,460 $ 213
Georgia investment portfolio liquidated 75,468      
Investment amortization     $ 8,676 $ 7,545