Loans and Allowance for Credit Losses - Recorded Investment and Unpaid Principal Balance for Impaired Loans with Associated Allowance (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Impaired [Line Items]
Recorded Investment	$ 35,487	$ 55,180
Unpaid Principal Balance	46,433	64,720
Related Allowance	711	395
Average Recorded Investment	36,490	47,071	$ 50,728
Interest Income Recognized	594	898	639
Commercial Financial Agricultural And Other With No Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	3,141	3,720
Unpaid Principal Balance	9,555	10,303
Average Recorded Investment	3,751	9,240	6,371
Interest Income Recognized	157	389	80
Commercial Financial Agricultural And Other With No Related Allowance [Member] | Time and demand loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	3,141	3,720
Unpaid Principal Balance	9,555	10,303
Average Recorded Investment	3,751	9,240	6,371
Interest Income Recognized	157	389	80
Commercial Financial Agricultural And Other With No Related Allowance [Member] | Equipment Finance
Financing Receivable, Impaired [Line Items]
Recorded Investment	0
Unpaid Principal Balance	0
Average Recorded Investment	0
Interest Income Recognized	0
Commercial Financial Agricultural And Other With No Related Allowance [Member] | Time and Demand Loans Other
Financing Receivable, Impaired [Line Items]
Recorded Investment	0
Unpaid Principal Balance	0
Average Recorded Investment	0
Interest Income Recognized	0
Real Estate Construction With No Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	45
Unpaid Principal Balance	0	53
Average Recorded Investment	0	53	146
Interest Income Recognized	0	0	14
Real Estate Construction With No Related Allowance [Member] | Construction Other
Financing Receivable, Impaired [Line Items]
Recorded Investment	0
Unpaid Principal Balance	0
Average Recorded Investment	0
Interest Income Recognized	0
Real Estate Construction With No Related Allowance [Member] | Construction Residential
Financing Receivable, Impaired [Line Items]
Recorded Investment	0
Unpaid Principal Balance	0
Average Recorded Investment	0
Interest Income Recognized	0
Residential real estate with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	9,145	9,365
Unpaid Principal Balance	11,010	11,294
Average Recorded Investment	9,040	10,315	11,913
Interest Income Recognized	241	375	335
Residential real estate with no related allowance recorded [Member] | Senior Lien
Financing Receivable, Impaired [Line Items]
Recorded Investment	5,754	5,200
Unpaid Principal Balance	6,848	6,337
Average Recorded Investment	5,280	5,674	6,605
Interest Income Recognized	172	279	241
Residential real estate with no related allowance recorded [Member] | Junior Lien
Financing Receivable, Impaired [Line Items]
Recorded Investment	3,391	4,165
Unpaid Principal Balance	4,162	4,957
Average Recorded Investment	3,760	4,641	5,308
Interest Income Recognized	69	96	94
Commercial Real Estate With No Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	21,505	40,591
Unpaid Principal Balance	24,119	41,525
Average Recorded Investment	22,983	26,235	22,287
Interest Income Recognized	172	119	184
Commercial Real Estate With No Related Allowance [Member] | Multifamily
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	14,677
Unpaid Principal Balance	0	14,677
Average Recorded Investment	172	1,223	1
Interest Income Recognized	43	0	0
Commercial Real Estate With No Related Allowance [Member] | Nonowner Occupied Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Recorded Investment	20,155	24,581
Unpaid Principal Balance	22,565	25,310
Average Recorded Investment	21,304	22,668	18,536
Interest Income Recognized	104	28	82
Commercial Real Estate With No Related Allowance [Member] | Owner Occupied Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Recorded Investment	1,350	1,333
Unpaid Principal Balance	1,554	1,538
Average Recorded Investment	1,507	2,344	3,750
Interest Income Recognized	25	91	102
Loans To Individuals With No Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	528	446
Unpaid Principal Balance	563	485
Average Recorded Investment	455	479	470
Interest Income Recognized	16	15	13
Loans To Individuals With No Related Allowance [Member] | Automobiles
Financing Receivable, Impaired [Line Items]
Recorded Investment	440	388
Unpaid Principal Balance	475	422
Average Recorded Investment	378	425	447
Interest Income Recognized	16	15	13
Loans To Individuals With No Related Allowance [Member] | Other consumer loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	88	58
Unpaid Principal Balance	88	63
Average Recorded Investment	77	54	23
Interest Income Recognized	0	0	0
Subtotal with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	34,319	54,167
Unpaid Principal Balance	45,247	63,660
Average Recorded Investment	36,229	46,322	41,187
Interest Income Recognized	586	898	626
Commercial, financial, agricultural and other With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	1,168	327
Unpaid Principal Balance	1,186	349
Related Allowance	711	307
Average Recorded Investment	261	84	1,544
Interest Income Recognized	8	0	3
Commercial, financial, agricultural and other With an allowance recorded [Member] | Time and demand loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	1,168	327
Unpaid Principal Balance	1,186	349
Related Allowance	711	307
Average Recorded Investment	261	84	1,544
Interest Income Recognized	8	0	3
Commercial, financial, agricultural and other With an allowance recorded [Member] | Equipment Finance
Financing Receivable, Impaired [Line Items]
Recorded Investment	0
Unpaid Principal Balance	0
Related Allowance	0
Average Recorded Investment	0
Interest Income Recognized	0
Commercial, financial, agricultural and other With an allowance recorded [Member] | Time and Demand Loans Other
Financing Receivable, Impaired [Line Items]
Recorded Investment	0
Unpaid Principal Balance	0
Related Allowance	0
Average Recorded Investment	0
Interest Income Recognized	0
Real estate construction with an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0	0
Interest Income Recognized	0	0	0
Real estate construction with an allowance recorded [Member] | Construction Other
Financing Receivable, Impaired [Line Items]
Recorded Investment	0
Unpaid Principal Balance	0
Related Allowance	0
Average Recorded Investment	0
Interest Income Recognized	0
Real estate construction with an allowance recorded [Member] | Construction Residential
Financing Receivable, Impaired [Line Items]
Recorded Investment	0
Unpaid Principal Balance	0
Related Allowance	0
Average Recorded Investment	0
Interest Income Recognized	0
Residential real estate With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0	0
Interest Income Recognized	0	0	0
Residential real estate With an allowance recorded [Member] | Senior Lien
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0	0
Interest Income Recognized	0	0	0
Residential real estate With an allowance recorded [Member] | Junior Lien
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0	0
Interest Income Recognized	0	0	0
Commercial real estate With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	686
Unpaid Principal Balance	0	711
Related Allowance	0	88
Average Recorded Investment	0	665	7,997
Interest Income Recognized	0	0	10
Commercial real estate With an allowance recorded [Member] | Multifamily
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	421
Unpaid Principal Balance	0	446
Related Allowance	0	88
Average Recorded Investment	0	444	395
Interest Income Recognized	0	0	0
Commercial real estate With an allowance recorded [Member] | Nonowner Occupied Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0	7,363
Interest Income Recognized	0	0	0
Commercial real estate With an allowance recorded [Member] | Owner Occupied Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	265
Unpaid Principal Balance	0	265
Related Allowance	0	0
Average Recorded Investment	0	221	239
Interest Income Recognized	0	0	10
Loans to individuals With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0	0
Interest Income Recognized	0	0	0
Loans to individuals With an allowance recorded [Member] | Automobiles
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0	0
Interest Income Recognized	0	0	0
Loans to individuals With an allowance recorded [Member] | Other consumer loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0	0
Interest Income Recognized	0	0	0
Subtotal With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	1,168	1,013
Unpaid Principal Balance	1,186	1,060
Related Allowance	711	395
Average Recorded Investment	261	749	9,541
Interest Income Recognized	$ 8	$ 0	$ 13