Securities - Amortized Cost and Estimated Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Amortized Cost	$ 322,345	$ 346,733
Unrealized Gains	2,620	3,899
Unrealized Losses	3,628	4,130
Fair Value	321,337	346,502
Federal agencies and GSEs
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Amortized Cost	114,246	106,379
Unrealized Gains	8	62
Unrealized Losses	2,127	2,387
Fair Value	112,127	104,054
Mortgage-backed and CMOs
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Amortized Cost	106,163	79,917
Unrealized Gains	293	514
Unrealized Losses	1,140	938
Fair Value	105,316	79,493
State and municipal
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Amortized Cost	92,711	145,757
Unrealized Gains	1,262	2,540
Unrealized Losses	347	782
Fair Value	93,626	147,515
Corporate
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Amortized Cost	7,842	13,392
Unrealized Gains	234	123
Unrealized Losses	14	23
Fair Value	8,062	13,492
Equity securities
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Amortized Cost	1,383	1,288
Unrealized Gains	823	660
Unrealized Losses	0	0
Fair Value	$ 2,206	$ 1,948

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
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