Securities Sold Under Agreements to Repurchase (Repurchase Agreements) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Gross Amounts of Recognized Liabilities	$ 26,418	$ 36,908
Gross Amounts Offset in the Statements of Condition	0	0
Net Amounts of Liabilities Presented in the Statements of Condition	26,418	36,908
Financial Instruments	(26,418)	(36,908)
Cash Collateral Pledged	0	0
Net Amount	0	0
Fair value of securities pledged in connection with repurchase agreements	54,319	$ 42,397
Total	26,418
U.S. Treasury and agency securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Total	26,418
Overnight and Continuous
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Total	26,418
Overnight and Continuous \| U.S. Treasury and agency securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Total	26,418
Up to 30 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Total	0
Up to 30 Days \| U.S. Treasury and agency securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Total	0
30 - 90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Total	0
30 - 90 Days \| U.S. Treasury and agency securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Total	0
Greater than 90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Total	0
Greater than 90 Days \| U.S. Treasury and agency securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Total	$ 0

Amount, before effects of master netting arrangements, of funds outstanding borrowed in the form of a financial asset repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same financial asset at a date certain for a specified price. Includes repurchase-to-maturity transactions and liabilities not subject to a master netting arrangement.

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Amount, after the effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Amount, after effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price offset against a right to receive collateral. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Amount of asset associated with funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price.

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Amount of right to receive cash collateral under master netting arrangements that have not been offset against securities sold under agreement to repurchase.

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Amount of right to receive securities collateral under master netting arrangements that have not been offset against securities sold under agreement to repurchase.

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Fair value of securities pledged as collateral against securities sold under agreement to repurchase.

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Amount, before effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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