Investment Securities (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position on other securities	$ (3,663,000)	$ (45,824,000)
Net investment gains/losses	(1,112,000)	24,917,000	8,774,000
Investment Securities (Textuals) [Abstract]
Federal Home Loan Bank Stock	121
Federal Reserve Bank Stock	70
Securities pledged as collateral	3,300,000,000	3,000,000,000
Obligations of state and political subdivisions (municipal securities)
Schedule of Available-for-sale Securities [Line Items]
Number of investment securities in an unrealized position less than Twelve months	4
Number of investment securities in an unrealized position for Twelve months or more	1
Unrealized loss position on other securities	(28,000)	(5,350,000)
Residential mortgage-related securities
Schedule of Available-for-sale Securities [Line Items]
Number of investment securities in an unrealized position less than Twelve months	38
Number of investment securities in an unrealized position for Twelve months or more	5
Unrealized loss position on other securities	(1,463,000)	(38,514,000)
Net investment gains/losses			3,000,000
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Number of investment securities in an unrealized position less than Twelve months	1
Number of individual trust preferred debt securities	3
Number of investment securities in an unrealized position for Twelve months or more	30
Unrealized loss position on other securities	(707,000)	(621,000)
Trust Preferred Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position on other securities	1,500,000
Other than temporary impairment			3,000,000
Federal agency securities
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position on other securities		$ (25,000)