Investment Securities Other Than Temporary Impairment Charges (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Investment [Line Items]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities	$ 2,910	$ 13,951	$ 13,401
Equity Securities [Member]
Investment [Line Items]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities	1,212	1,982	3,931
Financial Institutions Stock Portfolio [Member]
Investment [Line Items]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities	1,212	1,982	3,825
Mututal Funds [Member]
Investment [Line Items]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities	0	0	106
Debt Securities [Member]
Investment [Line Items]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities	1,698	11,969	9,470
Pooled Trust Preferred Securities [Member]
Investment [Line Items]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities	1,406	11,969	9,470
Auction Rate Securities [Member]
Investment [Line Items]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities	$ 292	$ 0	$ 0