Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Change in Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	$ 98,734	$ 109,191	$ 99,457	$ 117,306
Loans charged-off	(2,277)	(4,828)	(4,519)	(6,073)
Recoveries	3,967	3,660	6,346	7,291
Net (charge-offs) recoveries	1,690	(1,168)	1,827	1,218
PCL	2,716	(3,991)	1,856	(14,492)
Balance at end of period	103,140	104,032	103,140	104,032
Other Secured by 1-4 Family Residential Properties [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
PCL		1,600
Secured by 1-4 Family Residential Properties [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
PCL	6,700		9,600
Other Construction [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
PCL		1,400	8,200
Other Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
PCL	1,400
Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	98,734	109,191	99,457	117,306
Loans charged-off	(2,277)	(4,828)	(4,519)	(6,073)
Recoveries	3,967	3,660	6,346	7,291
PCL	(2,716)	(3,991)	1,856	(14,492)
Balance at end of period	103,140	104,032	103,140	104,032
Allowance for Credit Losses, ACL [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	7,351	5,058	6,079	6,854
Loans charged-off	(6)		(34)
Recoveries	344	313	1,187	1,079
PCL	(388)	(261)	69	(2,823)
Balance at end of period	7,301	5,110	7,301	5,110
Allowance for Credit Losses, ACL [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	9,867	8,667	10,310	9,928
Loans charged-off	(49)	(58)	(62)	(84)
Recoveries	206	181	295	252
PCL	14	1,609	(505)	303
Balance at end of period	10,038	10,399	10,038	10,399
Allowance for Credit Losses, ACL [Member] | Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	5,628	3,753	2,706	5,143
Loans charged-off	(79)	(4)	(79)	(4)
Recoveries		8	10	108
PCL	6,697	(847)	9,613	(2,337)
Balance at end of period	12,250	2,910	12,250	2,910
Allowance for Credit Losses, ACL [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	32,030	46,438	37,912	48,523
Loans charged-off	0	(79)		(79)
Recoveries		1,027	1,501	1,057
PCL	(3,769)	(2,970)	(9,678)	(5,085)
Balance at end of period	29,735	44,416	29,735	44,416
Allowance for Credit Losses, ACL [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	3,640	5,770	4,713	7,382
Loans charged-off	(131)		(131)
Recoveries		5	7	11
PCL	(216)	(464)	(1,292)	(2,082)
Balance at end of period	3,297	5,311	3,297	5,311
Allowance for Credit Losses, ACL [Member] | Commercial and Industrial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	14,951	20,166	18,939	14,851
Loans charged-off	(90)	(3,674)	(375)	(3,697)
Recoveries	203	652	303	1,939
PCL	(961)	(3,171)	(4,764)	880
Balance at end of period	14,103	13,973	14,103	13,973
Allowance for Credit Losses, ACL [Member] | Other Construction [Member] | Other Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	13,947	5,124	5,968	8,158
Loans charged-off	0
Recoveries		43	204	44
PCL	249	1,363	8,225	(1,672)
Balance at end of period	14,397	6,530	14,397	6,530
Allowance for Credit Losses, ACL [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	4,872	4,750	4,774	5,838
Loans charged-off	(357)	(391)	(936)	(833)
Recoveries	452	387	831	749
PCL	172	130	470	(878)
Balance at end of period	5,139	4,876	5,139	4,876
Allowance for Credit Losses, ACL [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	2,371	3,015	2,708	3,190
Loans charged-off
Recoveries
PCL	(454)	218	(791)	43
Balance at end of period	1,917	3,233	1,917	3,233
Allowance for Credit Losses, ACL [Member] | Other Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	4,077	6,450	5,348	7,439
Loans charged-off	(1,565)	(622)	(2,902)	(1,376)
Recoveries	1,079	1,044	2,008	2,052
PCL	1,372	402	509	(841)
Balance at end of period	$ 4,963	$ 7,274	$ 4,963	$ 7,274