Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Troubled Debt Restructuring Related to Loans Held for Investment, Excluding Covered Loans, by Loan Type (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Financing Receivable Modifications [Line Items]
Nonaccrual	$ 64,399	$ 62,698
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	3,931	5,878
Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	3,238	3,418
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	16,602	12,508
Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	13,164	12,775
Commercial and Industrial Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	15,922	19,328
Consumer Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	112	117
State and Other Political Subdivision Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	3,430	3,664
Other Commercial Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	239	$ 4,860
Troubled Debt Restructurings [Member]
Financing Receivable Modifications [Line Items]
Accruing	517		$ 1,542
Nonaccrual	22,754		21,407
Total	23,271		22,949
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
Nonaccrual	3,565		11
Total	3,565		11
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		42
Nonaccrual	939		3,644
Total	939		3,686
Troubled Debt Restructurings [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Accruing	0		0
Nonaccrual	12,266		3,846
Total	12,266		3,846
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	17
Nonaccrual	2,495
Total	2,512
Troubled Debt Restructurings [Member] | Commercial and Industrial Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing	500		1,500
Nonaccrual	198		10,073
Total	698		11,573
Troubled Debt Restructurings [Member] | Consumer Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing	0		0
Nonaccrual	3		15
Total	3		15
Troubled Debt Restructurings [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing	0		0
Nonaccrual	3,252		3,737
Total	3,252		3,737
Troubled Debt Restructurings [Member] | Other Commercial Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing	0		0
Nonaccrual	36		81
Total	$ 36		$ 81