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Fair Value Measurements (Narrative) (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2015	Apr. 15, 2015
Level 1 to Level 2 transfers, assets amount	$ 0	$ 0
Level 2 to Level 1 transfers, assets amount	0	0
Level 1 to Level 2 transfers, liabilities amount	0	0
Level 2 to Level 1 transfers, liabilities amount	0	0
Liabilities measured at fair value on nonrecurring basis	0	0
Assets measured at fair value on recurring basis using significant unobservable inputs	$ 0	$ 0
Subordinated Notes Due April 15, 2030 [Member]
Long-term borrowings			$ 40,000,000	$ 40,000,000

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- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

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- Definition

Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
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Amount of transfers of assets measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

+ References

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Amount of transfers of liabilities measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

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-Section 50
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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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- Definition

Aggregation of the liabilities reported on the balance sheet measured at fair value on a nonrecurring basis by the entity.

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