Annual report pursuant to Section 13 and 15(d)

Short-Term And Long-Term Investments And Restricted Deposits (Fair Value Of Available-For-Sale Investments With Gross Unrealized Losses By Investment Type And Length Of Time) (Details)

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Short-Term And Long-Term Investments And Restricted Deposits (Fair Value Of Available-For-Sale Investments With Gross Unrealized Losses By Investment Type And Length Of Time) (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2012
Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Unrealized Losses $ (490) $ (841)
Less Than 12 Months, Fair Value 121,901 61,948
12 Months or More, Unrealized Losses (2) 0
12 Months or More, Fair Value 202 0
U.S. Treasury Securities And Obligations Of U.S. Government Corporations And Agencies [Member]
    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Unrealized Losses (219) (13)
Less Than 12 Months, Fair Value 56,033 2,184
12 Months or More, Unrealized Losses (2) 0
12 Months or More, Fair Value 202 0
Corporate Securities [Member]
    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Unrealized Losses (198) (751)
Less Than 12 Months, Fair Value 44,758 23,040
12 Months or More, Unrealized Losses 0 0
12 Months or More, Fair Value 0 0
Municipal Securities, General Obligation [Member]
    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Unrealized Losses (26) (26)
Less Than 12 Months, Fair Value 8,464 3,710
12 Months or More, Unrealized Losses 0 0
12 Months or More, Fair Value 0 0
Municipal Securities, Revenue [Member]
    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Unrealized Losses (30) (34)
Less Than 12 Months, Fair Value 3,325 12,597
12 Months or More, Unrealized Losses 0 0
12 Months or More, Fair Value 0 0
Asset Backed Securities [Member]
    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Unrealized Losses (17) (17)
Less Than 12 Months, Fair Value 9,321 20,417
12 Months or More, Unrealized Losses 0 0
12 Months or More, Fair Value $ 0 $ 0