Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Impact of Modifications Classified as Troubled Debt Restructurings (Details) - Troubled Debt Restructurings [Member] $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021 USD ($) Contract	Jun. 30, 2020 USD ($) Contract	Jun. 30, 2021 USD ($) Contract	Jun. 30, 2020 USD ($) Contract
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract	13	8	16	19
Pre-Modification Outstanding Recorded Investment	$ 12,048	$ 4,253	$ 12,188	$ 6,356
Post-Modification Outstanding Recorded Investment	$ 12,048	$ 4,227	$ 12,188	$ 6,330
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract	5		5
Pre-Modification Outstanding Recorded Investment	$ 5,582		$ 5,582
Post-Modification Outstanding Recorded Investment	$ 5,582		$ 5,582
Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract	3	3	3	8
Pre-Modification Outstanding Recorded Investment	$ 37	$ 206	$ 37	$ 707
Post-Modification Outstanding Recorded Investment	$ 37	$ 210	$ 37	$ 711
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract	1	1	1	1
Pre-Modification Outstanding Recorded Investment	$ 377	$ 139	$ 377	$ 139
Post-Modification Outstanding Recorded Investment	$ 377	$ 139	$ 377	$ 139
Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract	1		3
Pre-Modification Outstanding Recorded Investment	$ 123		$ 249
Post-Modification Outstanding Recorded Investment	$ 123		$ 249
Commercial and Industrial Loans [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract	1		2	2
Pre-Modification Outstanding Recorded Investment	$ 1,000		$ 1,014	$ 1,582
Post-Modification Outstanding Recorded Investment	$ 1,000		$ 1,014	$ 1,582
Consumer Loans [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract		2		6
Pre-Modification Outstanding Recorded Investment		$ 6		$ 26
Post-Modification Outstanding Recorded Investment		$ 6		$ 26
State and Other Political Subdivision Loans [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract		2		2
Pre-Modification Outstanding Recorded Investment		$ 3,902		$ 3,902
Post-Modification Outstanding Recorded Investment		$ 3,872		$ 3,872
Other Commercial Loans [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract	2		2
Pre-Modification Outstanding Recorded Investment	$ 4,929		$ 4,929
Post-Modification Outstanding Recorded Investment	$ 4,929		$ 4,929