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Investments (Narrative) (Details) (USD $)
12 Months Ended
Dec. 31, 2011
Sep. 30, 2012
Gain (Loss) on Investments [Line Items]    
Held-to-maturity securities, unrealized losses $ 0 $ 0
Single largest loss position 501,000 477,000
Second largest loss position 70,000 56,000
Third largest loss position 58,000 51,000
Other-than-temporary impairments, available-for-sale securities $ 398,000  
Maximum [Member]
   
Gain (Loss) on Investments [Line Items]    
Percent of investment portfolio below investment grade   4.00%