Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Summary of Balance in Allowance for Loan Losses (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Total	$ 98,734	$ 99,457		$ 117,306
Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss	12,326	7,625
Collectively Evaluated for Credit Loss	86,408	91,832
Total	98,734	99,457	$ 109,191	117,306
Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss	46,547	44,361
Collectively Evaluated for Credit Loss	10,350,582	10,203,468
Total	10,397,129	10,247,829
Commercial and Industrial Loans [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss	2,797	5,750
Collectively Evaluated for Credit Loss	12,154	13,189
Total	14,951	18,939	20,166	14,851
Commercial and Industrial Loans [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss	15,271	18,444
Collectively Evaluated for Credit Loss	1,479,789	1,395,835
Total	1,495,060	1,414,279
Consumer Loans [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively Evaluated for Credit Loss	4,872	4,774
Total	4,872	4,774	4,750	5,838
Consumer Loans [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively Evaluated for Credit Loss	157,355	162,555
Total	157,355	162,555
State and Other Political Subdivision Loans [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss	1,160	1,394
Collectively Evaluated for Credit Loss	1,211	1,314
Total	2,371	2,708	3,015	3,190
State and Other Political Subdivision Loans [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss	3,430	3,664
Collectively Evaluated for Credit Loss	1,211,593	1,142,587
Total	1,215,023	1,146,251
Other Commercial Loans [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss	36	203
Collectively Evaluated for Credit Loss	4,041	5,145
Total	4,077	5,348	6,450	7,439
Other Commercial Loans [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss	36	4,608
Collectively Evaluated for Credit Loss	457,720	530,235
Total	457,756	534,843
Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss	666	278
Collectively Evaluated for Credit Loss	6,685	5,801
Total	7,351	6,079	5,058	6,854
Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss	3,707	5,198
Collectively Evaluated for Credit Loss	624,624	591,770
Total	628,331	596,968
Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively Evaluated for Credit Loss	9,867	10,310
Total	9,867	10,310	8,667	9,928
Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively Evaluated for Credit Loss	513,497	517,683
Total	513,497	517,683
Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively Evaluated for Credit Loss	32,030	37,912
Total	32,030	37,912	46,438	48,523
Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss	15,136	11,072
Collectively Evaluated for Credit Loss	2,959,903	2,966,012
Total	2,975,039	2,977,084
Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively Evaluated for Credit Loss	3,640	4,713
Total	3,640	4,713	5,770	7,382
Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss		56
Collectively Evaluated for Credit Loss	715,939	725,987
Total	715,939	726,043
Other Loans Secured by Real Estate [Member] | Other Construction [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss	7,667
Collectively Evaluated for Credit Loss	6,280	5,968
Total	13,947	5,968	5,124	8,158
Other Loans Secured by Real Estate [Member] | Other Construction [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss	7,667
Collectively Evaluated for Credit Loss	637,961	711,813
Total	645,628	711,813
Other Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively Evaluated for Credit Loss	5,628	2,706
Total	5,628	2,706	$ 3,753	$ 5,143
Other Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] | Allowance for Loan Losses, LHFI [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually Evaluated for Credit Loss	1,300	1,319
Collectively Evaluated for Credit Loss	1,592,201	1,458,991
Total	$ 1,593,501	$ 1,460,310