Deposits and Related Interest (Interest expense) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest Expense Domestic Deposit Liabilities [Abstract]
Demand and saving deposits	$ 11,426	$ 12,004	$ 12,414
Certificates of Deposits	18,872	17,249	14,620
Total	$ 30,298	$ 29,253	$ 27,034

Aggregate amount of interest expense on all deposits.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.6)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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- References

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- Definition

Amount of interest expense on domestic certificates of deposit liabilities.

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- Definition

The aggregate interest expense incurred on the following for deposits in domestic offices: (1) transaction accounts (NOW, and telephone and preauthorized transfer accounts), (2) money market deposits and (3) savings deposits.

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