Annual report pursuant to Section 13 and 15(d)

Short-Term And Long-Term Investments And Restricted Deposits (Short-Term And Long-Term Investments And Restricted Deposits By Investment Type) (Details)

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Short-Term And Long-Term Investments And Restricted Deposits (Short-Term And Long-Term Investments And Restricted Deposits By Investment Type) (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Schedule Of Investments And Restricted Deposits By Type [Line Items]    
Amortized Cost $ 945,129 $ 718,811
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments 4,788 8,833
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments (8,945) (487)
Fair Value 940,972 727,157
Mortgage-backed Securities Available-for-sale, Fair Value Disclosure 33,891 0
U.S. Treasury Securities And Obligations Of U.S. Government Corporations And Agencies [Member]
   
Schedule Of Investments And Restricted Deposits By Type [Line Items]    
Amortized Cost 246,085 110,941
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments 245 581
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments (7,494) (221)
Fair Value 238,836 111,301
Corporate Securities [Member]
   
Schedule Of Investments And Restricted Deposits By Type [Line Items]    
Amortized Cost 293,912 290,691
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments 2,782 4,615
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments (608) (195)
Fair Value 296,086 295,111
Restricted Certificates Of Deposit [Member]
   
Schedule Of Investments And Restricted Deposits By Type [Line Items]    
Amortized Cost 5,891 5,890
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments 0 0
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments 0 0
Fair Value 5,891 5,890
Restricted Cash Equivalents [Member]
   
Schedule Of Investments And Restricted Deposits By Type [Line Items]    
Amortized Cost 26,642 14,455
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments 0 0
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments 0 0
Fair Value 26,642 14,455
Municipal Securities, General Obligation [Member]
   
Schedule Of Investments And Restricted Deposits By Type [Line Items]    
Amortized Cost 54,003 85,440
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments 555 1,157
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments (136) (26)
Fair Value 54,422 86,571
Municipal Securities, Pre-Refunded [Member]
   
Schedule Of Investments And Restricted Deposits By Type [Line Items]    
Amortized Cost 10,835 5,337
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments 82 85
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments 0 0
Fair Value 10,917 5,422
Municipal Securities, Revenue [Member]
   
Schedule Of Investments And Restricted Deposits By Type [Line Items]    
Amortized Cost 68,801 82,781
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments 545 1,313
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments (292) (30)
Fair Value 69,054 84,064
Municipal Securities, Variable Rate Demand Notes [Member]
   
Schedule Of Investments And Restricted Deposits By Type [Line Items]    
Amortized Cost 28,575 23,385
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments 0 0
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments 0 0
Fair Value 28,575 23,385
Asset Backed Securities [Member]
   
Schedule Of Investments And Restricted Deposits By Type [Line Items]    
Amortized Cost 138,803 73,570
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments 579 1,082
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments (332) (15)
Fair Value 139,050 74,637
Mortgage backed securities
   
Schedule Of Investments And Restricted Deposits By Type [Line Items]    
Amortized Cost 33,974 0
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments 0 0
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments (83) 0
Fair Value 33,891 0
Cost And Equity Method Investments [Member]
   
Schedule Of Investments And Restricted Deposits By Type [Line Items]    
Amortized Cost 22,239 11,298
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments 0 0
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments 0 0
Fair Value 22,239 11,298
Life Insurance Contracts [Member]
   
Schedule Of Investments And Restricted Deposits By Type [Line Items]    
Amortized Cost 15,369 15,023
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments 0 0
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments 0 0
Fair Value $ 15,369 $ 15,023