Derivatives and Balance Sheet Offsetting Balance Sheet Offsetting (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Balance Sheet Offsetting [Line Items]
Repurchase agreements, amounts offset in balance sheet	$ 0	$ 0
Repurchase agreements, net amount presented in statement of financial position	73,182	105,080
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Securities	(73,182)	(105,080)
Securities sold under agreements to repurchase, amount not offset	0	0
Interest Rate Contracts [Member]
Balance Sheet Offsetting [Line Items]
Derivative Assets, Gross Amounts Offset in the Balance Sheets	0	0
Derivative Asset	14,548	11,800
Derivative, Collateral, Obligation to Return Securities	0	0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	14,548	11,800
Derivative Liability, Gross Amounts Offset in Balance Sheets	0	0
Derivative Liability	14,602	11,851
Derivative, Collateral, Right to Reclaim Securities	(14,602)	(11,851)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	0	0
Available-for-sale Securities [Member]
Balance Sheet Offsetting [Line Items]
Securities Sold under Agreements to Repurchase, Gross	73,182	105,080
Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Other Assets [Member]
Balance Sheet Offsetting [Line Items]
Fair value of asset derivative instruments	14,548	11,800
Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Other Liabilities [Member]
Balance Sheet Offsetting [Line Items]
Fair value of liability derivative instruments	$ 14,602	$ 11,851