Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Schedule of Amortized Cost Basis of Loans on Nonaccrual Status (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Financing Receivable Allowance For Credit Losses [Line Items]
Nonaccrual With No ACL	$ 18,667	$ 32,413
Total Nonaccrual	66,240	63,128
Loans Past Due 90 Days or More Still Accruing	625	1,576
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Nonaccrual With No ACL	4,911	5,756
Total Nonaccrual	5,629	5,985
Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Nonaccrual With No ACL	1,355	1,895
Total Nonaccrual	3,204	4,487
Loans Past Due 90 Days or More Still Accruing	154	79
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Nonaccrual With No ACL	11,319	12,037
Total Nonaccrual	13,077	15,197
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Nonaccrual With No ACL	56	60
Total Nonaccrual	175	185
Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Total Nonaccrual	12,562	11,807
Loans Past Due 90 Days or More Still Accruing	198	1,257
Commercial and Industrial Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Nonaccrual With No ACL	1,026	12,665
Total Nonaccrual	22,218	15,618
Consumer Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Total Nonaccrual	60	86
Loans Past Due 90 Days or More Still Accruing	273	240
State and Other Political Subdivision Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Total Nonaccrual	3,786	3,970
Other Commercial Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Total Nonaccrual	$ 5,529	$ 5,793