Allowance for Credit Losses, Credit Quality and Other - Summary of Aging Analysis for Loans Receivable (Detail) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	$ 15,180,624	$ 14,764,500
Accruing Loans Past Due 90 Days or More	7,031	5,034
Loans Past Due 30-59 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	17,174	15,145
Loans Past Due 60-89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	12,329	46,050
Loans Past Due 90 Days or More
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	96,292	98,887
Total Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	125,795	160,082
Current Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	15,054,829	14,604,418
Commercial real estate loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	8,564,669	8,499,987
Commercial real estate loans \| Non-farm/non-residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	5,553,182	5,426,780
Accruing Loans Past Due 90 Days or More	1,657	304
Commercial real estate loans \| Non-farm/non-residential \| Loans Past Due 30-59 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	1,836	4,352
Commercial real estate loans \| Non-farm/non-residential \| Loans Past Due 60-89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	2,760	38,944
Commercial real estate loans \| Non-farm/non-residential \| Loans Past Due 90 Days or More
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	35,974	36,172
Commercial real estate loans \| Non-farm/non-residential \| Total Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	40,570	79,468
Commercial real estate loans \| Non-farm/non-residential \| Current Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	5,512,612	5,347,312
Commercial real estate loans \| Construction/land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	2,695,561	2,736,214
Accruing Loans Past Due 90 Days or More	209	600
Commercial real estate loans \| Construction/land development \| Loans Past Due 30-59 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	1,745	369
Commercial real estate loans \| Construction/land development \| Loans Past Due 60-89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	393	799
Commercial real estate loans \| Construction/land development \| Loans Past Due 90 Days or More
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	1,762	4,302
Commercial real estate loans \| Construction/land development \| Total Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	3,900	5,470
Commercial real estate loans \| Construction/land development \| Current Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	2,691,661	2,730,744
Commercial real estate loans \| Agricultural
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	315,926	336,993
Accruing Loans Past Due 90 Days or More	0	0
Commercial real estate loans \| Agricultural \| Loans Past Due 30-59 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	124	90
Commercial real estate loans \| Agricultural \| Loans Past Due 60-89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	0	43
Commercial real estate loans \| Agricultural \| Loans Past Due 90 Days or More
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	519	559
Commercial real estate loans \| Agricultural \| Total Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	643	692
Commercial real estate loans \| Agricultural \| Current Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	315,283	336,301
Residential real estate loans \| Residential 1-4 family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	2,138,990	1,956,489
Accruing Loans Past Due 90 Days or More	3,459	1,835
Residential real estate loans \| Residential 1-4 family \| Loans Past Due 30-59 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	2,199	1,897
Residential real estate loans \| Residential 1-4 family \| Loans Past Due 60-89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	6,852	4,877
Residential real estate loans \| Residential 1-4 family \| Loans Past Due 90 Days or More
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	25,831	24,374
Residential real estate loans \| Residential 1-4 family \| Total Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	34,882	31,148
Residential real estate loans \| Residential 1-4 family \| Current Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	2,104,108	1,925,341
Residential real estate loans \| Multifamily residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	620,439	496,484
Accruing Loans Past Due 90 Days or More	0	0
Residential real estate loans \| Multifamily residential \| Loans Past Due 30-59 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	0	0
Residential real estate loans \| Multifamily residential \| Loans Past Due 60-89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	0	0
Residential real estate loans \| Multifamily residential \| Loans Past Due 90 Days or More
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	13,468	13,083
Residential real estate loans \| Multifamily residential \| Total Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	13,468	13,083
Residential real estate loans \| Multifamily residential \| Current Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	606,971	483,401
Total real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	11,324,098	10,952,960
Accruing Loans Past Due 90 Days or More	5,325	2,739
Total real estate \| Loans Past Due 30-59 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	5,904	6,708
Total real estate \| Loans Past Due 60-89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	10,005	44,663
Total real estate \| Loans Past Due 90 Days or More
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	77,554	78,490
Total real estate \| Total Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	93,463	129,861
Total real estate \| Current Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	11,230,635	10,823,099
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	1,218,834	1,234,361
Accruing Loans Past Due 90 Days or More	34	32
Consumer \| Loans Past Due 30-59 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	2,725	7,046
Consumer \| Loans Past Due 60-89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	22	68
Consumer \| Loans Past Due 90 Days or More
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	12,076	6,210
Consumer \| Total Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	14,823	13,324
Consumer \| Current Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	1,204,011	1,221,037
Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	2,107,326	2,022,775
Accruing Loans Past Due 90 Days or More	1,672	2,263
Commercial and industrial \| Loans Past Due 30-59 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	7,186	309
Commercial and industrial \| Loans Past Due 60-89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	1,558	1,028
Commercial and industrial \| Loans Past Due 90 Days or More
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	5,702	13,194
Commercial and industrial \| Total Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	14,446	14,531
Commercial and industrial \| Current Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	2,092,880	2,008,244
Agricultural & other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	530,366	554,404
Accruing Loans Past Due 90 Days or More	0	0
Agricultural & other \| Loans Past Due 30-59 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	1,359	1,082
Agricultural & other \| Loans Past Due 60-89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	744	291
Agricultural & other \| Loans Past Due 90 Days or More
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	960	993
Agricultural & other \| Total Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	3,063	2,366
Agricultural & other \| Current Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	$ 527,303	$ 552,038