Investment Securities (Details 4) (Available for sale investments, USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Available for sale investments
Reconciliation of credit-related impairment charges on investments recognized in earnings
Balance at the beginning	$ 8,665	$ 7,203	$ 8,416
Impairment charges recognized during period	166	258	415	7,461
Balance at the end	$ 8,831	$ 7,461	$ 8,831	$ 7,461