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, 2021	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Impaired [Line Items]
Recorded Investment	$ 55,180	$ 54,053
Unpaid Principal Balance	64,720	65,331
Related Allowance	395	4,906
Average Recorded Investment	47,071	50,728
Interest Income Recognized	898	639
Commercial Financial Agricultural And Other With No Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	3,720	2,025
Unpaid Principal Balance	10,303	2,725
Average Recorded Investment	9,240	6,371
Interest Income Recognized	389	80
Commercial Financial Agricultural And Other With No Related Allowance [Member] | Time and demand loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	3,720	2,025
Unpaid Principal Balance	10,303	2,725
Average Recorded Investment	9,240	6,371
Interest Income Recognized	389	80
Real Estate Construction With No Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	45	54
Unpaid Principal Balance	53	53
Average Recorded Investment	53	146
Interest Income Recognized	0	14
Residential real estate with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	9,365	10,939
Unpaid Principal Balance	11,294	13,258
Average Recorded Investment	10,315	11,913
Interest Income Recognized	375	335
Residential real estate with no related allowance recorded [Member] | Senior Lien
Financing Receivable, Impaired [Line Items]
Recorded Investment	5,200	6,062
Unpaid Principal Balance	6,337	7,575
Average Recorded Investment	5,674	6,605
Interest Income Recognized	279	241
Residential real estate with no related allowance recorded [Member] | Junior Lien
Financing Receivable, Impaired [Line Items]
Recorded Investment	4,165	4,877
Unpaid Principal Balance	4,957	5,683
Average Recorded Investment	4,641	5,308
Interest Income Recognized	96	94
Commercial Real Estate With No Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	40,591	20,650
Unpaid Principal Balance	41,525	23,641
Average Recorded Investment	26,235	22,287
Interest Income Recognized	119	184
Commercial Real Estate With No Related Allowance [Member] | Multifamily
Financing Receivable, Impaired [Line Items]
Recorded Investment	14,677	1
Unpaid Principal Balance	14,677	82
Average Recorded Investment	1,223	1
Interest Income Recognized	0	0
Commercial Real Estate With No Related Allowance [Member] | Nonowner Occupied Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Recorded Investment	24,581	16,786
Unpaid Principal Balance	25,310	19,459
Average Recorded Investment	22,668	18,536
Interest Income Recognized	28	82
Commercial Real Estate With No Related Allowance [Member] | Owner Occupied Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Recorded Investment	1,333	3,863
Unpaid Principal Balance	1,538	4,100
Average Recorded Investment	2,344	3,750
Interest Income Recognized	91	102
Loans To Individuals With No Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	446	418
Unpaid Principal Balance	485	447
Average Recorded Investment	479	470
Interest Income Recognized	15	13
Loans To Individuals With No Related Allowance [Member] | Automobiles
Financing Receivable, Impaired [Line Items]
Recorded Investment	388	405
Unpaid Principal Balance	422	430
Average Recorded Investment	425	447
Interest Income Recognized	15	13
Loans To Individuals With No Related Allowance [Member] | Other consumer loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	58	13
Unpaid Principal Balance	63	17
Average Recorded Investment	54	23
Interest Income Recognized	0	0
Subtotal with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	54,167	34,086
Unpaid Principal Balance	63,660	40,124
Average Recorded Investment	46,322	41,187
Interest Income Recognized	898	626
Commercial, financial, agricultural and other With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	327	4,210
Unpaid Principal Balance	349	9,377
Related Allowance	307	1,268
Average Recorded Investment	84	1,544
Interest Income Recognized	0	3
Commercial, financial, agricultural and other With an allowance recorded [Member] | Time and demand loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	327	4,210
Unpaid Principal Balance	349	9,377
Related Allowance	307	1,268
Average Recorded Investment	84	1,544
Interest Income Recognized	0	3
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
Interest Income Recognized	0	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
Interest Income Recognized	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
Interest Income Recognized	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
Interest Income Recognized	0	0
Commercial real estate With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	686	15,757
Unpaid Principal Balance	711	15,830
Related Allowance	88	3,638
Average Recorded Investment	665	7,997
Interest Income Recognized	0	10
Commercial real estate With an allowance recorded [Member] | Multifamily
Financing Receivable, Impaired [Line Items]
Recorded Investment	421	459
Unpaid Principal Balance	446	470
Related Allowance	88	116
Average Recorded Investment	444	395
Interest Income Recognized	0	0
Commercial real estate With an allowance recorded [Member] | Nonowner Occupied Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	15,060
Unpaid Principal Balance	0	15,122
Related Allowance	0	3,508
Average Recorded Investment	0	7,363
Interest Income Recognized	0	0
Commercial real estate With an allowance recorded [Member] | Owner Occupied Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Recorded Investment	265	238
Unpaid Principal Balance	265	238
Related Allowance	0	14
Average Recorded Investment	221	239
Interest Income Recognized	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
Interest Income Recognized	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
Interest Income Recognized	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
Interest Income Recognized	0	0
Subtotal With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	1,013	19,967
Unpaid Principal Balance	1,060	25,207
Related Allowance	395	4,906
Average Recorded Investment	749	9,541
Interest Income Recognized	$ 0	$ 13
Originated Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			$ 27,154
Interest Income Recognized			684
Originated Loans [Member] | Commercial Financial Agricultural And Other With No Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			2,411
Interest Income Recognized			66
Originated Loans [Member] | Real Estate Construction With No Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			0
Interest Income Recognized			0
Originated Loans [Member] | Residential real estate with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			10,819
Interest Income Recognized			365
Originated Loans [Member] | Commercial Real Estate With No Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			7,455
Interest Income Recognized			156
Originated Loans [Member] | Loans To Individuals With No Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			371
Interest Income Recognized			17
Originated Loans [Member] | Subtotal with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			21,056
Interest Income Recognized			604
Originated Loans [Member] | Commercial, financial, agricultural and other With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			4,110
Interest Income Recognized			77
Originated Loans [Member] | Real estate construction with an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			0
Interest Income Recognized			0
Originated Loans [Member] | Residential real estate With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			241
Interest Income Recognized			0
Originated Loans [Member] | Commercial real estate With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			1,747
Interest Income Recognized			3
Originated Loans [Member] | Loans to individuals With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			0
Interest Income Recognized			0
Originated Loans [Member] | Subtotal With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			6,098
Interest Income Recognized			80
Acquired Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			5,225
Interest Income Recognized			26
Acquired Loans [Member] | Commercial Financial Agricultural And Other With No Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			2,479
Interest Income Recognized			0
Acquired Loans [Member] | Real Estate Construction With No Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			0
Interest Income Recognized			0
Acquired Loans [Member] | Residential real estate with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			1,986
Interest Income Recognized			8
Acquired Loans [Member] | Commercial Real Estate With No Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			747
Interest Income Recognized			18
Acquired Loans [Member] | Loans To Individuals With No Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			13
Interest Income Recognized			0
Acquired Loans [Member] | Subtotal with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			5,225
Interest Income Recognized			26
Acquired Loans [Member] | Commercial, financial, agricultural and other With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			0
Interest Income Recognized			0
Acquired Loans [Member] | Real estate construction with an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			0
Interest Income Recognized			0
Acquired Loans [Member] | Residential real estate With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			0
Interest Income Recognized			0
Acquired Loans [Member] | Commercial real estate With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			0
Interest Income Recognized			0
Acquired Loans [Member] | Loans to individuals With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			0
Interest Income Recognized			0
Acquired Loans [Member] | Subtotal With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			0
Interest Income Recognized			$ 0