Loans and Allowance for Loan Losses - Impaired Loan Portfolio (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Financing Receivable, Impaired [Line Items]
Impaired loans with a valuation allowance, Related Allowance	$ 486		$ 486		$ 631
Total impaired loans, Recorded Investment	4,303		4,303		4,173
Total impaired loans, Unpaid Principal Balance	4,525		4,525		4,570
Total impaired loans, Average Recorded Investment	4,536	$ 5,946	4,519	$ 5,424
Total impaired loans, Interest Income Recognized	52	15	134	53
All Other Loans [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans without a valuation allowance, Recorded Investment	1,346		1,346		1,356
Impaired loans without a valuation allowance, Unpaid Principal Balance	1,346		1,346		1,361
Impaired loans with a valuation allowance, Recorded Investment	800		800		1,154
Impaired loans with a valuation allowance, Unpaid Principal Balance	800		800		1,154
Impaired loans with a valuation allowance, Related Allowance	486		486		475
Impaired loans without a valuation allowance, Average Recorded Investment	1,310	1,527	1,316	1,879
Impaired loans without a valuation allowance, Interest Income Recognized	6	10	24	43
Impaired loans with a valuation allowance, Average Recorded Investment	1,017	748	1,179	800
Impaired loans with a valuation allowance, Interest Income Recognized	6	5	27	17
All Other Loans [Member] \| Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans without a valuation allowance, Recorded Investment	551		551		256
Impaired loans without a valuation allowance, Unpaid Principal Balance	551		551		261
Impaired loans with a valuation allowance, Recorded Investment	0		0		0
Impaired loans with a valuation allowance, Unpaid Principal Balance	0		0		0
Impaired loans with a valuation allowance, Related Allowance	0		0		0
Impaired loans without a valuation allowance, Average Recorded Investment	552	258	374	435
Impaired loans without a valuation allowance, Interest Income Recognized	3	3	7	28
Impaired loans with a valuation allowance, Average Recorded Investment	198	0	198	12
Impaired loans with a valuation allowance, Interest Income Recognized	0	0	2	1
All Other Loans [Member] \| Consumer Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans without a valuation allowance, Recorded Investment	795		795		553
Impaired loans without a valuation allowance, Unpaid Principal Balance	795		795		553
Impaired loans with a valuation allowance, Recorded Investment	200		200		994
Impaired loans with a valuation allowance, Unpaid Principal Balance	200		200		994
Impaired loans with a valuation allowance, Related Allowance	78		78		343
Impaired loans without a valuation allowance, Average Recorded Investment	758	568	653	768
Impaired loans without a valuation allowance, Interest Income Recognized	3	4	17	8
Impaired loans with a valuation allowance, Average Recorded Investment	440	396	712	248
Impaired loans with a valuation allowance, Interest Income Recognized	4	4	18	6
All Other Loans [Member] \| Construction and Land Development [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans without a valuation allowance, Recorded Investment	0		0		547
Impaired loans without a valuation allowance, Unpaid Principal Balance	0		0		547
Impaired loans with a valuation allowance, Recorded Investment	0		0		0
Impaired loans with a valuation allowance, Unpaid Principal Balance	0		0		0
Impaired loans with a valuation allowance, Related Allowance	0		0		0
Impaired loans without a valuation allowance, Average Recorded Investment	0	701	289	637
Impaired loans without a valuation allowance, Interest Income Recognized	0	3	0	5
Impaired loans with a valuation allowance, Average Recorded Investment	0	0	0	14
Impaired loans with a valuation allowance, Interest Income Recognized	0	0	0	0
All Other Loans [Member] \| Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans without a valuation allowance, Recorded Investment	0		0		0
Impaired loans without a valuation allowance, Unpaid Principal Balance	0		0		0
Impaired loans with a valuation allowance, Recorded Investment	600		600		160
Impaired loans with a valuation allowance, Unpaid Principal Balance	600		600		160
Impaired loans with a valuation allowance, Related Allowance	408		408		132
Impaired loans without a valuation allowance, Average Recorded Investment	0	0	0	25
Impaired loans without a valuation allowance, Interest Income Recognized	0	0	0	1
Impaired loans with a valuation allowance, Average Recorded Investment	379	352	269	498
Impaired loans with a valuation allowance, Interest Income Recognized	2	1	7	10
All Other Loans [Member] \| Consumer and Other [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans without a valuation allowance, Recorded Investment	0		0		0
Impaired loans without a valuation allowance, Unpaid Principal Balance	0		0		0
Impaired loans with a valuation allowance, Recorded Investment	0		0		0
Impaired loans with a valuation allowance, Unpaid Principal Balance	0		0		0
Impaired loans with a valuation allowance, Related Allowance	0		0		0
Impaired loans without a valuation allowance, Average Recorded Investment	0	0	0	14
Impaired loans without a valuation allowance, Interest Income Recognized	0	0	0	1
Impaired loans with a valuation allowance, Average Recorded Investment	0	0	0	28
Impaired loans with a valuation allowance, Interest Income Recognized	0	0	0	0
Purchased Credit Impaired Loans [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with a valuation allowance, Recorded Investment	2,157		2,157		1,663
Impaired loans with a valuation allowance, Unpaid Principal Balance	2,379		2,379		2,055
Impaired loans with a valuation allowance, Related Allowance	0		0		156
Impaired loans with a valuation allowance, Average Recorded Investment	2,209	3,671	2,024	2,745
Impaired loans with a valuation allowance, Interest Income Recognized	40	0	83
Impaired loans with a valuation allowance, Interest Income (Expense) Recognized				(7)
Purchased Credit Impaired Loans [Member] \| Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with a valuation allowance, Recorded Investment	0		0		17
Impaired loans with a valuation allowance, Unpaid Principal Balance	0		0		99
Impaired loans with a valuation allowance, Related Allowance	0		0		17
Impaired loans with a valuation allowance, Average Recorded Investment	8	2,520	250	1,894
Impaired loans with a valuation allowance, Interest Income Recognized	0	0	1
Impaired loans with a valuation allowance, Interest Income (Expense) Recognized				(10)
Purchased Credit Impaired Loans [Member] \| Consumer Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with a valuation allowance, Recorded Investment	1,852		1,852		1,205
Impaired loans with a valuation allowance, Unpaid Principal Balance	2,113		2,113		1,371
Impaired loans with a valuation allowance, Related Allowance	0		0		74
Impaired loans with a valuation allowance, Average Recorded Investment	1,869	1,151	1,344	851
Impaired loans with a valuation allowance, Interest Income Recognized	38	0	77	3
Purchased Credit Impaired Loans [Member] \| Construction and Land Development [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with a valuation allowance, Recorded Investment	0		0		0
Impaired loans with a valuation allowance, Unpaid Principal Balance	0		0		0
Impaired loans with a valuation allowance, Related Allowance	0		0		0
Impaired loans with a valuation allowance, Average Recorded Investment	0	0	58	0
Impaired loans with a valuation allowance, Interest Income Recognized	0	0	0	0
Purchased Credit Impaired Loans [Member] \| Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with a valuation allowance, Recorded Investment	279		279		396
Impaired loans with a valuation allowance, Unpaid Principal Balance	242		242		534
Impaired loans with a valuation allowance, Related Allowance	0		0		59
Impaired loans with a valuation allowance, Average Recorded Investment	305	0	343	0
Impaired loans with a valuation allowance, Interest Income Recognized	2	0	5	0
Purchased Credit Impaired Loans [Member] \| Consumer and Other [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with a valuation allowance, Recorded Investment	26		26		45
Impaired loans with a valuation allowance, Unpaid Principal Balance	24		24		51
Impaired loans with a valuation allowance, Related Allowance	0		0		$ 6
Impaired loans with a valuation allowance, Average Recorded Investment	27	0	29	0
Impaired loans with a valuation allowance, Interest Income Recognized	$ 0	$ 0	$ 0	$ 0

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Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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