Loans and Allowance for Credit Losses - Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	$ 101,309	$ 51,637
Ending Balance	92,522	101,309	$ 51,637
Ending balance: individually evaluated for impaired	395	4,906	2,432
Ending balance: collectively evaluated for impaired	92,127	96,403	49,205
Ending balance: individually evaluated for impaired			17,833
Ending balance: collectively evaluated for impaired			6,171,315
Financing receivable, before allowance for credit loss	6,839,230	6,761,183
Financing Receivable, Allowance for Credit Loss, Writeoff	(13,058)	(19,250)
Recoveries	4,648	2,057
Provision for credit losses	(377)	53,472
Loans	6,839,230	6,761,183	6,189,148
Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance: individually evaluated for impaired	43,531	41,463
Ending balance: collectively evaluated for impaired	6,795,699	6,719,720
Financing receivable, before allowance for credit loss	6,839,230	6,761,183
Time and demand loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing receivable, before allowance for credit loss	1,159,524	1,541,382
Commercial credit cards
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing receivable, before allowance for credit loss	13,928	14,604
Senior Lien
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing receivable, before allowance for credit loss	1,299,534	1,144,323
Junior Lien
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing receivable, before allowance for credit loss	620,716	606,269
Multifamily
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing receivable, before allowance for credit loss	385,432	371,239
Nonowner Occupied Commercial Real Estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing receivable, before allowance for credit loss	1,465,247	1,421,151
Owner Occupied Commercial Real Estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing receivable, before allowance for credit loss	400,418	419,179
Consumer Credit Cards
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing receivable, before allowance for credit loss	11,151	12,360
Other consumer loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing receivable, before allowance for credit loss	87,544	90,655
Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	13,393
Ending Balance		13,393
Commercial, financial, agricultural and other [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	17,187	20,234
Ending Balance	18,093	17,187	20,234
Ending balance: individually evaluated for impaired	307	1,268	1,580
Ending balance: collectively evaluated for impaired	17,786	15,919	18,654
Ending balance: individually evaluated for impaired			9,246
Ending balance: collectively evaluated for impaired			1,232,607
Financing Receivable, Allowance for Credit Loss, Writeoff	(7,020)	(6,318)
Recoveries	2,430	314
Provision for credit losses	5,496	1,479
Loans			1,241,853
Commercial, financial, agricultural and other [Member] | Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance: individually evaluated for impaired	3,032	5,411
Ending balance: collectively evaluated for impaired	1,170,420	1,550,575
Financing receivable, before allowance for credit loss	1,173,452	1,555,986
Commercial, financial, agricultural and other [Member] | Time and demand loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	16,838	0
Ending Balance	17,846	16,838	0
Ending balance: individually evaluated for impaired	307	1,268
Ending balance: collectively evaluated for impaired	17,539	15,570
Financing Receivable, Allowance for Credit Loss, Writeoff	(6,845)	(6,220)
Recoveries	2,412	301
Provision for credit losses	5,441	1,515
Commercial, financial, agricultural and other [Member] | Time and demand loans | Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance: individually evaluated for impaired	3,032	5,411
Ending balance: collectively evaluated for impaired	1,156,492	1,535,971
Financing receivable, before allowance for credit loss	1,159,524	1,541,382
Commercial, financial, agricultural and other [Member] | Commercial credit cards
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	349	0
Ending Balance	247	349	0
Ending balance: individually evaluated for impaired	0	0
Ending balance: collectively evaluated for impaired	247	349
Financing Receivable, Allowance for Credit Loss, Writeoff	(175)	(98)
Recoveries	18	13
Provision for credit losses	55	(36)
Commercial, financial, agricultural and other [Member] | Commercial credit cards | Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance: individually evaluated for impaired	0	0
Ending balance: collectively evaluated for impaired	13,928	14,604
Financing receivable, before allowance for credit loss	13,928	14,604
Commercial, financial, agricultural and other [Member] | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	1,478
Ending Balance		1,478
Commercial, financial, agricultural and other [Member] | Cumulative Effect, Period of Adoption, Adjustment | Time and demand loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	21,242
Ending Balance		21,242
Commercial, financial, agricultural and other [Member] | Cumulative Effect, Period of Adoption, Adjustment | Commercial credit cards
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	470
Ending Balance		470
Real Estate Construction [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	7,966	2,558
Ending Balance	4,220	7,966	2,558
Ending balance: individually evaluated for impaired	0	0	0
Ending balance: collectively evaluated for impaired	4,220	7,966	2,558
Ending balance: individually evaluated for impaired			0
Ending balance: collectively evaluated for impaired			449,039
Financing Receivable, Allowance for Credit Loss, Writeoff	(9)	0
Recoveries	155	26
Provision for credit losses	(3,892)	4,820
Loans			449,039
Real Estate Construction [Member] | Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance: individually evaluated for impaired	0	0
Ending balance: collectively evaluated for impaired	494,456	427,221
Financing receivable, before allowance for credit loss	494,456	427,221
Real Estate Construction [Member] | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	562
Ending Balance		562
Commercial real estate [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	41,953	19,768
Ending Balance	33,376	41,953	19,768
Ending balance: individually evaluated for impaired	88	3,638	851
Ending balance: collectively evaluated for impaired	33,288	38,315	18,917
Ending balance: individually evaluated for impaired			6,846
Ending balance: collectively evaluated for impaired			2,110,673
Financing Receivable, Allowance for Credit Loss, Writeoff	(1,659)	(4,939)
Recoveries	135	312
Provision for credit losses	(7,053)	27,019
Loans			2,117,519
Commercial real estate [Member] | Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance: individually evaluated for impaired	40,246	34,947
Ending balance: collectively evaluated for impaired	2,210,851	2,176,622
Financing receivable, before allowance for credit loss	2,251,097	2,211,569
Commercial real estate [Member] | Multifamily
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	6,240	0
Ending Balance	3,561	6,240	0
Ending balance: individually evaluated for impaired	88	116
Ending balance: collectively evaluated for impaired	3,473	6,124
Financing Receivable, Allowance for Credit Loss, Writeoff	(1)	0
Recoveries	0	0
Provision for credit losses	(2,678)	4,593
Commercial real estate [Member] | Multifamily | Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance: individually evaluated for impaired	15,097	459
Ending balance: collectively evaluated for impaired	370,335	370,780
Financing receivable, before allowance for credit loss	385,432	371,239
Commercial real estate [Member] | Nonowner Occupied Commercial Real Estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	28,414	0
Ending Balance	24,838	28,414	0
Ending balance: individually evaluated for impaired	0	3,508
Ending balance: collectively evaluated for impaired	24,838	24,906
Financing Receivable, Allowance for Credit Loss, Writeoff	(1,556)	(4,678)
Recoveries	125	187
Provision for credit losses	(2,145)	20,588
Commercial real estate [Member] | Nonowner Occupied Commercial Real Estate | Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance: individually evaluated for impaired	24,205	31,450
Ending balance: collectively evaluated for impaired	1,441,042	1,389,701
Financing receivable, before allowance for credit loss	1,465,247	1,421,151
Commercial real estate [Member] | Owner Occupied Commercial Real Estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	7,299	0
Ending Balance	4,977	7,299	0
Ending balance: individually evaluated for impaired	0	14
Ending balance: collectively evaluated for impaired	4,977	7,285
Financing Receivable, Allowance for Credit Loss, Writeoff	(102)	(261)
Recoveries	10	125
Provision for credit losses	(2,230)	1,838
Commercial real estate [Member] | Owner Occupied Commercial Real Estate | Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance: individually evaluated for impaired	944	3,038
Ending balance: collectively evaluated for impaired	399,474	416,141
Financing receivable, before allowance for credit loss	400,418	419,179
Commercial real estate [Member] | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	(207)
Ending Balance		(207)
Commercial real estate [Member] | Cumulative Effect, Period of Adoption, Adjustment | Multifamily
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	1,647
Ending Balance		1,647
Commercial real estate [Member] | Cumulative Effect, Period of Adoption, Adjustment | Nonowner Occupied Commercial Real Estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	12,317
Ending Balance		12,317
Commercial real estate [Member] | Cumulative Effect, Period of Adoption, Adjustment | Owner Occupied Commercial Real Estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	5,597
Ending Balance		5,597
Loans To Individuals [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	19,845	4,984
Ending Balance	24,208	19,845	4,984
Ending balance: individually evaluated for impaired	0	0	0
Ending balance: collectively evaluated for impaired	24,208	19,845	4,984
Ending balance: individually evaluated for impaired			0
Ending balance: collectively evaluated for impaired			699,375
Financing Receivable, Allowance for Credit Loss, Writeoff	(4,061)	(6,953)
Recoveries	1,460	991
Provision for credit losses	6,964	16,539
Loans			699,375
Loans To Individuals [Member] | Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance: individually evaluated for impaired	0	0
Ending balance: collectively evaluated for impaired	999,975	815,815
Financing receivable, before allowance for credit loss	999,975	815,815
Loans To Individuals [Member] | Automobiles
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	16,133	0
Ending Balance	21,392	16,133	0
Ending balance: individually evaluated for impaired	0	0
Ending balance: collectively evaluated for impaired	21,392	16,133
Financing Receivable, Allowance for Credit Loss, Writeoff	(1,792)	(3,954)
Recoveries	1,016	745
Provision for credit losses	6,035	13,236
Loans To Individuals [Member] | Automobiles | Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance: individually evaluated for impaired	0	0
Ending balance: collectively evaluated for impaired	901,280	712,800
Financing receivable, before allowance for credit loss	901,280	712,800
Loans To Individuals [Member] | Consumer Credit Cards
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	635	0
Ending Balance	496	635	0
Ending balance: individually evaluated for impaired	0	0
Ending balance: collectively evaluated for impaired	496	635
Financing Receivable, Allowance for Credit Loss, Writeoff	(425)	(595)
Recoveries	71	36
Provision for credit losses	215	973
Loans To Individuals [Member] | Consumer Credit Cards | Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance: individually evaluated for impaired	0	0
Ending balance: collectively evaluated for impaired	11,151	12,360
Financing receivable, before allowance for credit loss	11,151	12,360
Loans To Individuals [Member] | Other consumer loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	3,077	0
Ending Balance	2,320	3,077	0
Ending balance: individually evaluated for impaired	0	0
Ending balance: collectively evaluated for impaired	2,320	3,077
Financing Receivable, Allowance for Credit Loss, Writeoff	(1,844)	(2,404)
Recoveries	373	210
Provision for credit losses	714	2,330
Loans To Individuals [Member] | Other consumer loans | Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance: individually evaluated for impaired	0	0
Ending balance: collectively evaluated for impaired	87,544	90,655
Financing receivable, before allowance for credit loss	87,544	90,655
Loans To Individuals [Member] | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	4,284
Ending Balance		4,284
Loans To Individuals [Member] | Cumulative Effect, Period of Adoption, Adjustment | Automobiles
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	6,106
Ending Balance		6,106
Loans To Individuals [Member] | Cumulative Effect, Period of Adoption, Adjustment | Consumer Credit Cards
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	221
Ending Balance		221
Loans To Individuals [Member] | Cumulative Effect, Period of Adoption, Adjustment | Other consumer loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	2,941
Ending Balance		2,941
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	14,358	4,093
Ending Balance	12,625	14,358	4,093
Ending balance: individually evaluated for impaired	0	0	1
Ending balance: collectively evaluated for impaired	12,625	14,358	4,092
Ending balance: individually evaluated for impaired			1,741
Ending balance: collectively evaluated for impaired			1,679,621
Financing Receivable, Allowance for Credit Loss, Writeoff	(309)	(1,040)
Recoveries	468	414
Provision for credit losses	(1,892)	3,615
Loans			1,681,362
Residential Real Estate [Member] | Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance: individually evaluated for impaired	253	1,105
Ending balance: collectively evaluated for impaired	1,919,997	1,749,487
Financing receivable, before allowance for credit loss	1,920,250	1,750,592
Residential Real Estate [Member] | Senior Lien
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	7,919	0
Ending Balance	7,459	7,919	0
Ending balance: individually evaluated for impaired	0	0
Ending balance: collectively evaluated for impaired	7,459	7,919
Financing Receivable, Allowance for Credit Loss, Writeoff	(60)	(550)
Recoveries	337	296
Provision for credit losses	(737)	847
Residential Real Estate [Member] | Senior Lien | Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance: individually evaluated for impaired	0	528
Ending balance: collectively evaluated for impaired	1,299,534	1,143,795
Financing receivable, before allowance for credit loss	1,299,534	1,144,323
Residential Real Estate [Member] | Junior Lien
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	6,439	0
Ending Balance	5,166	6,439	0
Ending balance: individually evaluated for impaired	0	0
Ending balance: collectively evaluated for impaired	5,166	6,439
Financing Receivable, Allowance for Credit Loss, Writeoff	(249)	(490)
Recoveries	131	118
Provision for credit losses	(1,155)	2,768
Residential Real Estate [Member] | Junior Lien | Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance: individually evaluated for impaired	253	577
Ending balance: collectively evaluated for impaired	620,463	605,692
Financing receivable, before allowance for credit loss	620,716	606,269
Residential Real Estate [Member] | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	7,276
Ending Balance		7,276
Residential Real Estate [Member] | Cumulative Effect, Period of Adoption, Adjustment | Senior Lien
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	7,326
Ending Balance		7,326
Residential Real Estate [Member] | Cumulative Effect, Period of Adoption, Adjustment | Junior Lien
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	$ 4,043
Ending Balance		4,043
Originated Loans [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance		51,585	47,586
Ending Balance			51,585
Financing Receivable, Allowance for Credit Loss, Writeoff			(10,032)
Recoveries			1,449
Provision for credit losses			12,582
Originated Loans [Member] | Commercial, financial, agricultural and other [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance		20,221	19,235
Ending Balance			20,221
Financing Receivable, Allowance for Credit Loss, Writeoff			(2,667)
Recoveries			245
Provision for credit losses			3,408
Originated Loans [Member] | Real Estate Construction [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance		2,558	2,002
Ending Balance			2,558
Financing Receivable, Allowance for Credit Loss, Writeoff			0
Recoveries			158
Provision for credit losses			398
Originated Loans [Member] | Commercial real estate [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance		19,731	18,382
Ending Balance			19,731
Financing Receivable, Allowance for Credit Loss, Writeoff			(632)
Recoveries			189
Provision for credit losses			1,792
Originated Loans [Member] | Loans To Individuals [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance		4,984	4,033
Ending Balance			4,984
Financing Receivable, Allowance for Credit Loss, Writeoff			(5,747)
Recoveries			611
Provision for credit losses			6,087
Originated Loans [Member] | Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance		4,091	3,934
Ending Balance			4,091
Financing Receivable, Allowance for Credit Loss, Writeoff			(986)
Recoveries			246
Provision for credit losses			897
Acquired Loans [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance		52	178
Ending Balance			52
Financing Receivable, Allowance for Credit Loss, Writeoff			(2,242)
Recoveries			165
Provision for credit losses			1,951
Acquired Loans [Member] | Commercial, financial, agricultural and other [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance		13	139
Ending Balance			13
Financing Receivable, Allowance for Credit Loss, Writeoff			(726)
Recoveries			81
Provision for credit losses			519
Acquired Loans [Member] | Real Estate Construction [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance		0	0
Ending Balance			0
Financing Receivable, Allowance for Credit Loss, Writeoff			0
Recoveries			0
Provision for credit losses			0
Acquired Loans [Member] | Commercial real estate [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance		37	4
Ending Balance			37
Financing Receivable, Allowance for Credit Loss, Writeoff			(1,376)
Recoveries			0
Provision for credit losses			1,409
Acquired Loans [Member] | Loans To Individuals [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance		0	0
Ending Balance			0
Financing Receivable, Allowance for Credit Loss, Writeoff			(84)
Recoveries			15
Provision for credit losses			69
Acquired Loans [Member] | Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance		$ 2	35
Ending Balance			2
Financing Receivable, Allowance for Credit Loss, Writeoff			(56)
Recoveries			69
Provision for credit losses			$ (46)