Investments (Details 4) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Amortized Cost, Due in one year or less	$ 67,748
Amortized Cost, Due after one year through five years	167,458
Amortized Cost, Due after five years through ten years	101,673
Amortized Cost, Amortized Cost Due after ten years	51,259
Debt Maturities, Amortized Cost	397,800
Fair Value, Due in one year or less	68,739
Fair Value, Due after one year through five years	169,811
Fair Value, Due after five years through ten years	102,770
Fair Value, Due after ten years	50,391
Debt Securities, Fair Value	401,435	380,469
Collateralized Mortgage Backed Securities [Member]
Debt Maturities, Amortized Cost	9,662
Debt Securities, Fair Value	$ 9,724	$ 4,137