Loans and The Allowance for Loan Losses - Activity in Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Beginning Allowance	$ 20,877	$ 18,750
Provision (credit) for loan losses	(460)	57
Loans charged-off	(240)	(15)
Recoveries	8	83
Loans and Leases Receivable, Ending Allowance	20,185	18,875
Consumer, Excluding Consumer Other Portfolio Segment \| 1-4 Family Residential
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Beginning Allowance	5,076	4,846
Provision (credit) for loan losses	23	80
Loans charged-off	0	0
Recoveries	0	74
Loans and Leases Receivable, Ending Allowance	5,099	5,000
Consumer, Excluding Consumer Other Portfolio Segment \| Home Equity
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Beginning Allowance	699	537
Provision (credit) for loan losses	(68)	21
Loans charged-off	0	0
Recoveries	0	0
Loans and Leases Receivable, Ending Allowance	631	558
Consumer, Excluding Consumer Other Portfolio Segment \| Commercial Real Estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Beginning Allowance	9,584	8,374
Provision (credit) for loan losses	121	(41)
Loans charged-off	(194)	0
Recoveries	0	0
Loans and Leases Receivable, Ending Allowance	9,511	8,333
Consumer and Commercial Portfolio Segment \| Construction
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Beginning Allowance	1,708	1,353
Provision (credit) for loan losses	(427)	104
Loans charged-off	0	0
Recoveries	0	0
Loans and Leases Receivable, Ending Allowance	1,281	1,457
Commercial business
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Beginning Allowance	3,473	3,206
Provision (credit) for loan losses	(95)	(89)
Loans charged-off	(25)	0
Recoveries	0	9
Loans and Leases Receivable, Ending Allowance	3,353	3,126
Consumer
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Beginning Allowance	337	434
Provision (credit) for loan losses	(14)	(18)
Loans charged-off	(21)	(15)
Recoveries	8	0
Loans and Leases Receivable, Ending Allowance	$ 310	$ 401

Amount of recovery of financing receivables doubtful of collection that were previously charged off.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of direct write-downs of financing receivables charged against the allowance.

+ References

+ Details

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- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 6.L.1)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74567-122707

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (b)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544

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- Definition

Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

+ References

+ Details

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