Investment Securities (Details Textual) (USD $)	12 Months Ended						12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 CMO's / REMIC's - Residential [Member] Y	Feb. 29, 2008 CMO's / REMIC's - Residential [Member]	Dec. 31, 2006 CMO's / REMIC's - Residential [Member] Score Security	Dec. 31, 2011 Municipal Bonds [Member] Y
Investments Securities (Textual) [Abstract]
Securities issued by U.S Government, Percentage	70.00%
Gross realized gain	$ 0	$ 38,900,000	$ 28,400,000
Gross realized losses	0	0	0
CMO/REMIC's backed by whole loans issued by private-label companies (non-government sponsored)				4,800,000
Investment security classified as held-to-maturity, number						1
Held-to-maturity securities, average FICO score						715
Investment securities held-to-maturity	2,383,000	3,143,000		2,400,000
Held-to-maturity securities, acquired price, percentage					98.25%
Fair value percentage of held-to-maturity security against par value				57.00%
Average percentage of LTV						71.00%
Average life of investment grade debt securities, years				3.0			9.8
Investment contractual cash flows guaranteed by Government, percentage				99.68%
Investment contractual cash flows guaranteed by banks, percentage				0.32%
Gross Unrealized Holding Losses				0
Loss on securities greater than 12 months							0
Investment securities pledged as collateral	1,850,000,000	1,740,000,000
Contractual maturity, years				30 years
Impairment loss				0
Impairment loss on investment securities	254,000	317,000	1,994,000
Plus: Reclassification of credit-related impairment loss recorded in other comprehensive income			1,700,000
Credit-related impairment loss on investment securities held-to-maturity	656,000	904,000	323,000
Net impairment losses	$ 1,900,000