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, 2020	Dec. 31, 2019
Financing Receivable, Recorded Investment, Aging [Abstract]
Nonaccrual With No ACL	$ 22,922
Total Nonaccrual	53,856	$ 53,226
Loans Past Due 90 Days or More Still Accruing	782
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Nonaccrual With No ACL	517
Total Nonaccrual	786	897
Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Nonaccrual With No ACL	1,928
Total Nonaccrual	4,298
Loans Past Due 90 Days or More Still Accruing	299
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Nonaccrual With No ACL	6,951
Total Nonaccrual	10,272	7,700
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Nonaccrual With No ACL	61
Total Nonaccrual	565	1,032
Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Nonaccrual		16,810
Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Nonaccrual	11,087
Loans Past Due 90 Days or More Still Accruing	359
Commercial and Industrial Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Nonaccrual With No ACL	13,465
Total Nonaccrual	16,813	21,775
Consumer Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Nonaccrual	96	108
Loans Past Due 90 Days or More Still Accruing	124
State and Other Political Subdivision Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Nonaccrual	4,019	$ 4,079
Other Commercial Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Nonaccrual	$ 5,920