Loans - Impaired Loan Data (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Unpaid Contractual Principal Balance
With No Related Allowance Recorded	$ 8,670	$ 20,129
With An Allowance Recorded	5,584	7,876
Loans Including Purchased Credit Impaired Loans	15,363	28,384
Recorded Investment
With No Related Allowance Recorded	7,795	19,249
With An Allowance Recorded	5,584	7,865
Loans Including Purchased Credit Impaired Loans	14,381	27,361
Related Allowance
With An Allowance Recorded	993	1,925
Total Impaired Loans	1,127	2,010
Average Recorded Investment
With No Related Allowance Recorded	15,079	17,376
With An Allowance Recorded	6,609	7,766
Loans Including Purchased Credit Impaired Loans	22,400	25,476
Purchase credit impaired
Unpaid Contractual Principal Balance
Loans Including Purchased Credit Impaired Loans	1,109	379
Recorded Investment
Loans Including Purchased Credit Impaired Loans	1,002	247
Related Allowance
With An Allowance Recorded	134	85
Purchased Credit Impaired Loans	134	85
Average Recorded Investment
Loans Including Purchased Credit Impaired Loans	712	334
Residential real estate
Unpaid Contractual Principal Balance
With No Related Allowance Recorded	1,194	1,140
With An Allowance Recorded	778	1,274
Loans Including Purchased Credit Impaired Loans	1,983	2,428
Recorded Investment
With No Related Allowance Recorded	1,194	1,122
With An Allowance Recorded	778	1,230
Loans Including Purchased Credit Impaired Loans	1,980	2,363
Related Allowance
With An Allowance Recorded	113	226
Total Impaired Loans	121	230
Average Recorded Investment
With No Related Allowance Recorded	1,105	2,142
With An Allowance Recorded	1,093	703
Loans Including Purchased Credit Impaired Loans	2,206	2,858
Residential real estate | Purchase credit impaired
Unpaid Contractual Principal Balance
Loans Including Purchased Credit Impaired Loans	11	14
Recorded Investment
Loans Including Purchased Credit Impaired Loans	8	11
Related Allowance
With An Allowance Recorded	8	4
Purchased Credit Impaired Loans	8	4
Average Recorded Investment
Loans Including Purchased Credit Impaired Loans	8	13
Commercial, financial & agricultural
Unpaid Contractual Principal Balance
With No Related Allowance Recorded	80	42
With An Allowance Recorded	0	310
Loans Including Purchased Credit Impaired Loans	135	407
Recorded Investment
With No Related Allowance Recorded	80	40
With An Allowance Recorded	0	310
Loans Including Purchased Credit Impaired Loans	127	396
Related Allowance
With An Allowance Recorded	0	263
Total Impaired Loans	4	263
Average Recorded Investment
With No Related Allowance Recorded	52	203
With An Allowance Recorded	99	1,118
Loans Including Purchased Credit Impaired Loans	195	1,370
Commercial, financial & agricultural | Purchase credit impaired
Unpaid Contractual Principal Balance
Loans Including Purchased Credit Impaired Loans	55	55
Recorded Investment
Loans Including Purchased Credit Impaired Loans	47	46
Related Allowance
With An Allowance Recorded	4	0
Purchased Credit Impaired Loans	4	0
Average Recorded Investment
Loans Including Purchased Credit Impaired Loans	44	49
Consumer and other
Unpaid Contractual Principal Balance
With No Related Allowance Recorded	0	0
With An Allowance Recorded	0	0
Loans Including Purchased Credit Impaired Loans	192	192
Recorded Investment
With No Related Allowance Recorded	0	0
With An Allowance Recorded	0	0
Loans Including Purchased Credit Impaired Loans	96	96
Related Allowance
With An Allowance Recorded	0	0
Total Impaired Loans	96	81
Average Recorded Investment
With No Related Allowance Recorded	0	0
With An Allowance Recorded	2	0
Loans Including Purchased Credit Impaired Loans	74	113
Consumer and other | Purchase credit impaired
Unpaid Contractual Principal Balance
Loans Including Purchased Credit Impaired Loans	192	192
Recorded Investment
Loans Including Purchased Credit Impaired Loans	96	96
Related Allowance
With An Allowance Recorded	96	81
Purchased Credit Impaired Loans	96	81
Average Recorded Investment
Loans Including Purchased Credit Impaired Loans	72	113
Construction, land and land development
Unpaid Contractual Principal Balance
With No Related Allowance Recorded	62	6,969
With An Allowance Recorded	0	0
Loans Including Purchased Credit Impaired Loans	62	7,087
Recorded Investment
With No Related Allowance Recorded	61	6,982
With An Allowance Recorded	0	0
Loans Including Purchased Credit Impaired Loans	61	7,076
Related Allowance
With An Allowance Recorded	0	0
Total Impaired Loans	0	0
Average Recorded Investment
With No Related Allowance Recorded	5,373	2,841
With An Allowance Recorded	0	0
Loans Including Purchased Credit Impaired Loans	5,437	2,937
Construction, land and land development | Purchase credit impaired
Unpaid Contractual Principal Balance
Loans Including Purchased Credit Impaired Loans	0	118
Recorded Investment
Loans Including Purchased Credit Impaired Loans	0	94
Related Allowance
With An Allowance Recorded	0	0
Purchased Credit Impaired Loans	0	0
Average Recorded Investment
Loans Including Purchased Credit Impaired Loans	64	96
Commercial real estate
Unpaid Contractual Principal Balance
With No Related Allowance Recorded	7,334	11,978
With An Allowance Recorded	4,806	6,292
Loans Including Purchased Credit Impaired Loans	12,991	18,270
Recorded Investment
With No Related Allowance Recorded	6,460	11,105
With An Allowance Recorded	4,806	6,325
Loans Including Purchased Credit Impaired Loans	12,117	17,430
Related Allowance
With An Allowance Recorded	880	1,436
Total Impaired Loans	906	1,436
Average Recorded Investment
With No Related Allowance Recorded	8,549	12,190
With An Allowance Recorded	5,415	5,945
Loans Including Purchased Credit Impaired Loans	14,488	18,198
Commercial real estate | Purchase credit impaired
Unpaid Contractual Principal Balance
Loans Including Purchased Credit Impaired Loans	851	0
Recorded Investment
Loans Including Purchased Credit Impaired Loans	851	0
Related Allowance
With An Allowance Recorded	26	0
Purchased Credit Impaired Loans	26	0
Average Recorded Investment
Loans Including Purchased Credit Impaired Loans	$ 524	$ 63