Federal Home Loan Bank and Federal Reserve Bank Borrowings (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
FHLB Fixed Rate Advances, Maturities Summary [Abstract]
FHLB Fixed Rate Advances, Weighted Average Interest Rate, Within 1 year	0.27%
FHLB Fixed Rate Advances, Amount, Within 1 year	$ 210,000
Federal Home Loan Bank, Advances, Maturities Summary, Average Interest Rate, One To Five Years From Balance Sheet Date	5.66%
FHLB Fixed Rate Advances, Over 1 through 5 years	1,000
FHLB Fixed Rate Advances, Weighted Average Interest Rate, Due after 10 years	5.37%
FHLB Fixed Rate Advances, Due after 10 years	5,000
FHLB Fixed Rate Advances, Total Amount before valuation adjustment	216,000
Valuation adjustment from acquisition accounting	568
FHLB Fixed Rate Advances, Total Amount	216,568
Federal Home Loan Bank, Advances, Activity for Year [Abstract]
FHLB Advances	216,568	36,606	6,644
Average balance during the year	44,876	51,030	100,337
Maximum month-end balance during the year	216,568	190,631	118,967
Weighted average rate during the year	0.74%	1.12%	2.79%
Weighted average rate at December 31	0.41%	1.09%	5.42%
FHLB Advances, Collateral Pledged	1,083,879	1,075,389
FHLB Borrowing Capacity	865,138	1,037,159
Federal Reserve Bank, Advances, Collateral Pledged	86,130	85,452
Federal Reserve Bank borrowing capacity	86,130	85,452
Securities Investment [Member]
Federal Home Loan Bank, Advances, Activity for Year [Abstract]
Federal Reserve Bank, Advances, Collateral Pledged	40,128	40,210
Loans Receivable [Member]
Federal Home Loan Bank, Advances, Activity for Year [Abstract]
FHLB Advances, Collateral Pledged	1,083,879	1,075,389
Commercial Loan [Member]
Federal Home Loan Bank, Advances, Activity for Year [Abstract]
Federal Reserve Bank, Advances, Collateral Pledged	$ 46,002	$ 45,242

Federal Home Loan Bank, Advances, Maturities Summary, Average Interest Rate, after Ten Years from Balance Sheet Date

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Federal Home Loan Bank, Advances, Maturities Summary, Weighted Average Interest Rate, One To Five Years From Balance Sheet Date

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Federal Home Loan Bank, Advances, Maturities Summary by Interest Rate Type, Fixed Rate, after Ten Years

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Federal Home Loan Bank, Advances, Maturities Summary by Interest Rate Type, Fixed Rate, Before Valuation Adjustment

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Federal Home Loan Bank, Fixed Rate Advances, Valuation Adjustment From Acquisition Accounting

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Federal Reserve Bank, Advances, Collateral Pledged

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Federal Reserve Bank, Advances, Maximum Amount Available

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The calculated average balance outstanding for the year for all Federal Home Loan Bank advances as of the Balance Sheet date.

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The calculated weighted average interest rate for Federal Home Loan Bank advances outstanding as of the Balance Sheet date.

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The calculated weighted average interest rate for Federal Home Loan Bank advances for the period ended as of the Balance Sheet date.

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The maximum balance outstanding at any month end during the period as of the Balance Sheet date.

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Amount of the collateral pledged in support of federal home loan bank advances outstanding.

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Amount of maximum advances or credit lines available from the Federal Home Loan Bank (FHLB).

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Including both current and noncurrent portions, Federal Home Loan Bank borrowings initially due beyond one year or beyond the normal operating cycle if longer.

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The weighted average interest rate applicable to the Federal Home Loan Bank advances which are due within one year of the Balance Sheet date.

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Amount of Federal Home Loan Bank (FHLB) advances which have fixed interest.

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Amount of Federal Home Loan Bank (FHLB) advances which have fixed interest rates maturing between the next fiscal year and the fifth fiscal year following the latest fiscal year.

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Amount of Federal Home Loan Bank (FHLB) advances which have fixed interest rates maturing in the next fiscal year following the latest fiscal year.

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