Loan and Lease Finance Receivables and Allowance for Credit Losses (Details Textual) (USD $)	6 Months Ended	9 Months Ended	12 Months Ended																		12 Months Ended
	Jun. 30, 2011	Sep. 30, 2011 Covered_Loan	Dec. 31, 2011 Performing_Loan	Dec. 31, 2010	Dec. 31, 2011 Commercial Real Estate Loans [Member]	Dec. 31, 2011 Dairy and Livestock Loans [Member]	Dec. 31, 2011 Nonaccrual dairy and livestock loans [Member]	Dec. 31, 2011 Non-covered impaired loans modified in troubled debt restructure [Member]	Dec. 31, 2011 Performing Financing Receivable [Member]	Dec. 31, 2011 Nonperforming Financing Receivable [Member]	Dec. 31, 2011 Nonaccrual single family mortgage loans [Member]	Dec. 31, 2011 Allowance impaired loans [Member]	Dec. 31, 2010 Allowance impaired Noncovered Loans [Member]	Dec. 31, 2011 Construction [Member]	Dec. 31, 2011 Nonaccrual commercial and industrial loans [Member]	Dec. 31, 2011 Nonaccrual residential construction and land loans [Member]	Dec. 31, 2011 Nonaccrual commercial construction loans [Member]	Dec. 31, 2011 Commercial Real Estate Loans [Member]	Dec. 31, 2011 Nonaccrual consumer loans [Member]	Dec. 31, 2011 Nonaccrual commercial real estate loans [Member]	Dec. 31, 2011 Covered loans held for sale activity [Member]	Dec. 31, 2010 Covered loans held for sale activity [Member]	Sep. 30, 2011 Covered loans held for sale activity [Member]	Dec. 31, 2009 Covered loans held for sale activity [Member]	Dec. 31, 2011 Nonaccrual non-covered impaired loans [Member]	Dec. 31, 2011 Non-covered impaired loans [Member]	Dec. 31, 2010 Non-covered impaired loans [Member]
Loans and Lease Finance Receivables (Textual) [Abstract]
Fixed rate loans held			$ 1,310,000,000
Percentage of loan portfolio														2.70%				61.50%
Transfers of loans to held for sale	6,000,000																				5,726,000
Charge-off against allowance for credit losses	619,000
Write-down of loans held for sale		1,700,000																			0	0
Loans classified as troubled debt restructured			62,400,000						38,600,000	23,800,000
Loans held-for-sale				2,954,000																	5,664,000	0	5,700,000	0
Outstanding balance			62,672,000	157,020,000	886,000	3,400,000	2,500,000				17,000,000				3,500,000	920,000	12,400,000		478,000	26,000,000
Impaired, at carrying value			101,226,000	170,294,000				62,400,000				3,000,000	4,100,000												23,800,000	101,200,000	170,300,000
Loans and Lease Finance Receivables (Additional Textual) [Abstract]
Number of covered loans held for sale		12
Number of performing loans			16
Allocation of allowance to troubled debt restructuring			$ 27,000	$ 0