Derivatives and Balance Sheet Offsetting Balance Sheet Offsetting (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Balance Sheet Offsetting [Line Items]
Repurchase agreements, amounts offset in balance sheet	$ 0	$ 0
Repurchase agreements, net amount presented in statement of financial position	65,895	80,822
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Securities	(65,895)	(80,822)
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	9,077	9,012
Derivative, Collateral, Obligation to Return Securities	0	0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	9,077	9,012
Derivative Liability, Gross Amounts Offset in Balance Sheets	0	0
Derivative Liability	9,096	9,036
Derivative, Collateral, Right to Reclaim Securities	(9,096)	(9,036)
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	65,895	80,822
Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Other Assets [Member]
Balance Sheet Offsetting [Line Items]
Fair value of asset derivative instruments	9,077	9,012
Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Other Liabilities [Member]
Balance Sheet Offsetting [Line Items]
Fair value of liability derivative instruments	$ 9,096	$ 9,036