LHFI and ACL, LHFI - Troubled Debt Restructuring Related to Loans Held for Investment, Excluding Covered Loans, by Loan Type (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable Modifications [Line Items]
Nonaccrual	$ 62,698	$ 63,128
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	5,878	5,985
Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	12,775	11,807
Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	3,418	4,487
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	12,508	15,197
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	150	185
Commercial and Industrial Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	19,328	15,618
Consumer Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	117	86
State and Other Political Subdivision Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	3,664	3,970
Other Commercial Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	4,860	5,793
Troubled Debt Restructurings [Member]
Financing Receivable Modifications [Line Items]
Accruing	2,451	1,506	$ 3,396
Nonaccrual	19,160	24,254	28,127
Total	21,611	25,760	31,523
Troubled Debt Restructurings [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Accruing	0	0	0
Nonaccrual	4,640	12	15
Total	4,640	12	15
Troubled Debt Restructurings [Member] | Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Accruing			77
Nonaccrual			3,865
Total			3,942
Troubled Debt Restructurings [Member] | Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Accruing	50
Nonaccrual	2,484
Total	2,534
Troubled Debt Restructurings [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Accruing	0	0
Nonaccrual	965	3,699
Total	965	3,699
Troubled Debt Restructurings [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Accruing	394	0	0
Nonaccrual	7,325	3,903	5,176
Total	7,719	3,903	5,176
Troubled Debt Restructurings [Member] | Commercial and Industrial Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing	2,000	1,500	3,319
Nonaccrual	215	12,749	18,913
Total	2,215	14,249	22,232
Troubled Debt Restructurings [Member] | Consumer Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing	7	6	0
Nonaccrual	9	17	21
Total	16	23	21
Troubled Debt Restructurings [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing	0	0
Nonaccrual	3,486	3,793
Total	3,486	3,793
Troubled Debt Restructurings [Member] | Other Commercial Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing	0	0
Nonaccrual	36	81
Total	$ 36	$ 81
Troubled Debt Restructurings [Member] | Other Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing			0
Nonaccrual			137
Total			$ 137