Loans and Allowance for Loan Losses - Changes in allowance (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Changes in the allowance
Beginning Balance	$ 23,924	$ 22,174
Provision for loan losses	2,500	2,220
Loan charge-offs	(99)	(1,948)
Loan recoveries	694	192
Ending Balance	27,019	22,638
Unallocated
Changes in the allowance
Beginning Balance	2,192	1,177
Provision for loan losses	(359)	(1,168)
Ending Balance	1,833	9
Commercial
Changes in the allowance
Beginning Balance	19,261	18,656
Provision for loan losses	1,689	2,973
Loan charge-offs	(32)	(1,786)
Loan recoveries	593	66
Ending Balance	21,511	19,909
Commercial \| Commercial and industrial
Changes in the allowance
Beginning Balance	12,270	12,127
Provision for loan losses	70	3,407
Loan charge-offs	(32)	(1,785)
Loan recoveries	593	66
Ending Balance	12,901	13,815
Commercial \| Real estate construction
Changes in the allowance
Beginning Balance	303	250
Provision for loan losses	31	2
Loan charge-offs		(1)
Ending Balance	334	251
Commercial \| Commercial real estate
Changes in the allowance
Beginning Balance	6,688	6,279
Provision for loan losses	1,588	(436)
Ending Balance	8,276	5,843
Consumer
Changes in the allowance
Beginning Balance	2,471	2,341
Provision for loan losses	1,170	415
Loan charge-offs	(67)	(162)
Loan recoveries	101	126
Ending Balance	3,675	2,720
Consumer \| Residential \| Real estate first mortgage
Changes in the allowance
Beginning Balance	1,448	1,156
Provision for loan losses	761	454
Ending Balance	2,209	1,610
Consumer \| Residential \| Real estate junior lien
Changes in the allowance
Beginning Balance	671	805
Provision for loan losses	317	7
Loan charge-offs		(104)
Loan recoveries	37	53
Ending Balance	1,025	761
Consumer \| Other revolving and installment
Changes in the allowance
Beginning Balance	352	380
Provision for loan losses	92	(46)
Loan charge-offs	(67)	(58)
Loan recoveries	64	73
Ending Balance	$ 441	$ 349

Amount of increase in allowance for credit loss on accounts receivable, from recovery.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (e)
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- Definition

Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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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.

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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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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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.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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