Other Borrowings and Notes Payable (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Nov. 06, 2012
Debt Instrument [Line Items]
Securities sold under repurchase agreements	$ 230,373,000	$ 200,021,000
Secured borrowings	3,810,000us-gaap_SecuredDebt	3,810,000us-gaap_SecuredDebt
Total	234,183,000us-gaap_OtherBorrowings	203,831,000us-gaap_OtherBorrowings
Line of Credit
Debt Instrument [Line Items]
Remaining borrowing capacity	663,500,000
Aggregate of pledge secured by certain eligible loans	805,200,000
Amount withdrawn	0
Other Borrowings
Debt Instrument [Line Items]
Average balance during the year	184,964,000	197,556,000
Maximum balance outstanding at any month-end	234,183,000	214,439,000
Average interest rate during the year	0.32%	0.32%
Average interest rate at December 31	0.30%	0.31%
Unsecured Term Loan
Debt Instrument [Line Items]
Average balance during the year	6,464,000	11,241,000
Maximum balance outstanding at any month-end	6,900,000	11,700,000
Average interest rate during the year	2.99%	3.52%
Average interest rate at December 31	2.94%	3.44%
Unsecured term loan, face amount			12,000,000
Term Loan	$ 5,700,000	$ 10,500,000

Short-term and Long-term Debt, Average Outstanding Amount

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Short-term and Long-term Debt, Maximum Month-end Outstanding Amount

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Face (par) amount of debt instrument at time of issuance.

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The effective interest rate at the end of the reporting period.

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The average effective interest rate during the reporting period.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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Including the current and noncurrent portions, aggregate carrying value as of the balance sheet date of loans payable (with maturities initially due after one year or beyond the operating cycle if longer).

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The carrying amount as of the balance sheet date for the aggregate of other miscellaneous borrowings owed by the reporting entity.

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The carrying amount, as of the date of the latest financial statement presented, of loans receivable which are owned but transferred to serve as collateral for the payment of FHLB debt obligations, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

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Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

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Amount, after the effects of master netting arrangements, of funds outstanding borrowed in the form of a security resale agreement between the entity and another party for the purchase and resale of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement.

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