Loans, Allowance for Credit Losses and Impaired Loans - Loan Impairment and Allowance for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Allowance for credit losses
Beginning Balance	$ 7,304	$ 7,063	$ 7,063
Charge-offs	(170)	(341)
Recoveries	37	41
Provisions for credit losses	648	300
Ending Balance	7,819	7,063	7,304
Individually evaluated for impairment: Balance in allowance	478		572
Individually evaluated for impairment: Related loan balance	21,251		18,324
Collectively evaluated for impairment: Balance in allowance	7,341		6,732
Collectively evaluated for impairment: Related loan balance	993,938		975,664
Unamortized discounts on acquired loans	5,533		6,136
Non-accrual loans
Loans past due 90 days or more still accruing interest	293		5
Construction and Land Development
Allowance for credit losses
Beginning Balance	602	647	647
Charge-offs		(11)
Recoveries		1
Provisions for credit losses	116	(39)
Ending Balance	718	598	602
Residential Real Estate
Allowance for credit losses
Beginning Balance	1,380	1,521	1,521
Charge-offs	(25)
Recoveries	4	2
Provisions for credit losses	60	(14)
Ending Balance	1,419	1,509	1,380
Nonresidential
Allowance for credit losses
Beginning Balance	4,074	3,629	3,629
Charge-offs	(38)	(191)
Recoveries	3	4
Provisions for credit losses	304	254
Ending Balance	4,343	3,696	4,074
Home Equity Loans
Allowance for credit losses
Beginning Balance	142	122	122
Charge-offs		(4)
Recoveries	10
Provisions for credit losses	17	29
Ending Balance	169	147	142
Real Estate Mortgage \| Construction and Land Development
Allowance for credit losses
Individually evaluated for impairment: Related loan balance	388		723
Collectively evaluated for impairment: Balance in allowance	718		602
Collectively evaluated for impairment: Related loan balance	90,106		84,028
Real Estate Mortgage \| Residential Real Estate
Allowance for credit losses
Individually evaluated for impairment: Balance in allowance	181		216
Individually evaluated for impairment: Related loan balance	4,417		3,905
Collectively evaluated for impairment: Balance in allowance	1,238		1,164
Collectively evaluated for impairment: Related loan balance	202,064		205,381
Non-accrual loans
Loans past due 90 days or more still accruing interest	293
Real Estate Mortgage \| Nonresidential
Allowance for credit losses
Individually evaluated for impairment: Balance in allowance	90		82
Individually evaluated for impairment: Related loan balance	14,287		11,449
Collectively evaluated for impairment: Balance in allowance	4,253		3,991
Collectively evaluated for impairment: Related loan balance	540,973		533,100
Real Estate Mortgage \| Home Equity Loans
Allowance for credit losses
Individually evaluated for impairment: Related loan balance	56		9
Collectively evaluated for impairment: Balance in allowance	169		142
Collectively evaluated for impairment: Related loan balance	37,373		37,706
Commercial
Allowance for credit losses
Beginning Balance	826	641	641
Charge-offs	(66)	(98)
Recoveries	7	18
Provisions for credit losses	118	94
Ending Balance	885	655	826
Individually evaluated for impairment: Balance in allowance	207		274
Individually evaluated for impairment: Related loan balance	2,086		2,238
Collectively evaluated for impairment: Balance in allowance	678		552
Collectively evaluated for impairment: Related loan balance	117,485		109,759
Consumer and Other
Allowance for credit losses
Beginning Balance	14	13	13
Charge-offs	(41)	(37)
Recoveries	13	16
Provisions for credit losses	33	19
Ending Balance	19	11	14
Individually evaluated for impairment: Related loan balance	17
Collectively evaluated for impairment: Balance in allowance	19		14
Collectively evaluated for impairment: Related loan balance	5,937		5,690
Non-accrual loans
Loans past due 90 days or more still accruing interest			5
Unallocated
Allowance for credit losses
Beginning Balance	266	490	490
Provisions for credit losses		(43)
Ending Balance	266	$ 447	266
Collectively evaluated for impairment: Balance in allowance	$ 266		$ 267

Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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

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The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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The balance of financing receivables that were collectively evaluated for impairment.

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Amount of financing receivable 90 days or more past due and still accruing.

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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.

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Amount of expense related to estimated loss from loan and lease transactions.

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Amount of deferred fees paid by borrowers and unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of loans that are being amortized into income as an adjustment to yield. Excludes amounts for loans and leases covered under loss sharing agreements.

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