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Fair Value (Narrative) (Details) (USD $)
 9 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Schedule of Available-for-sale Securities [Line Items]    
Long-term investments $ 12,100,000  
Unrealized Losses Still Held 1,533,000 2,976,000
Fair value of auction rate securities 10,600,000  
Unrealized gains on long-term Investments $ 300,000 $ 400,000
Minimum [Member]
    
Schedule of Available-for-sale Securities [Line Items]    
Interest rates reset period 7 days  
Maturity term 10 years  
Maximum [Member]
    
Schedule of Available-for-sale Securities [Line Items]    
Interest rates reset period 35 days