Derivatives and Balance Sheet Offsetting Balance Sheet Offsetting (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Balance Sheet Offsetting [Line Items]
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement	$ 79,059
Repurchase agreements, amounts offset in balance sheet	0	$ 0
repurchase agreements, net amount presented in statement of financial position	79,059	80,822
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Securities	(79,059)	(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	6,707	9,012
Derivative, Collateral, Obligation to Return Securities	0	0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	6,707	9,012
Derivative Liability, Gross Amounts Offset in Balance Sheets	0	0
Derivative Liability	6,714	9,036
Derivative, Collateral, Right to Reclaim Securities	(6,714)	(9,036)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	0	0
Available-for-sale Securities [Member]
Balance Sheet Offsetting [Line Items]
Assets Sold under Agreements to Repurchase, Term, Carrying Amounts	25,000
Assets Sold under Agreements to Repurchase, Carrying Amount	79,059	$ 80,822
Assets Sold under Agreements to Repurchase, Sweep, Carrying Amount	$ 54,100