Derivatives and Balance Sheet Offsetting Balance Sheet Offsetting (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Balance Sheet Offsetting [Line Items]
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement	$ 46,229
Repurchase agreements, amounts offset in balance sheet	0	$ 0
Repurchase agreements, net amount presented in statement of financial position	46,229	79,059
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Securities	(46,229)	(79,059)
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	8,624	6,707
Derivative, Collateral, Obligation to Return Securities	0	0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	8,624	6,707
Derivative Liability, Gross Amounts Offset in Balance Sheets	0	0
Derivative Liability	8,624	6,714
Derivative, Collateral, Right to Reclaim Securities	(1,708)	(6,714)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	6,916	0
Available-for-sale Securities [Member]
Balance Sheet Offsetting [Line Items]
Securities Sold under Agreements to Repurchase, Gross	46,229	79,059
Not Designated as Hedging Instrument [Member] \| Interest Rate Contracts [Member] \| Other Assets [Member]
Balance Sheet Offsetting [Line Items]
Fair value of asset derivative instruments	8,624	6,707
Not Designated as Hedging Instrument [Member] \| Interest Rate Contracts [Member] \| Other Liabilities [Member]
Balance Sheet Offsetting [Line Items]
Fair value of liability derivative instruments	8,624	$ 6,714
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member]
Balance Sheet Offsetting [Line Items]
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement	46,229
Maturity Overnight [Member] \| U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member]
Balance Sheet Offsetting [Line Items]
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement	$ 46,229

[Line Items] for Balance Sheet Offsetting [Table]

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