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		9 Months Ended
	Sep. 30, 2021 USD ($) Contract	Sep. 30, 2020 USD ($) Contract	Sep. 30, 2021 USD ($) Contract	Sep. 30, 2020 USD ($) Contract
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract	4	4	20	23
Pre-Modification Outstanding Recorded Investment	$ 635	$ 135	$ 12,823	$ 6,491
Post-Modification Outstanding Recorded Investment	$ 635	$ 136	$ 12,823	$ 6,466
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract			5
Pre-Modification Outstanding Recorded Investment			$ 5,582
Post-Modification Outstanding Recorded Investment			$ 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	11
Pre-Modification Outstanding Recorded Investment		$ 87	$ 37	$ 794
Post-Modification Outstanding Recorded Investment		$ 89	$ 37	$ 800
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract	3		4	1
Pre-Modification Outstanding Recorded Investment	$ 483		$ 860	$ 139
Post-Modification Outstanding Recorded Investment	$ 483		$ 860	$ 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		4
Pre-Modification Outstanding Recorded Investment	$ 152		$ 401
Post-Modification Outstanding Recorded Investment	$ 152		$ 401
Commercial and Industrial Loans [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract		1	2	3
Pre-Modification Outstanding Recorded Investment		$ 48	$ 1,014	$ 1,630
Post-Modification Outstanding Recorded Investment		$ 47	$ 1,014	$ 1,629
Consumer Loans [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract				6
Pre-Modification Outstanding Recorded Investment				$ 26
Post-Modification Outstanding Recorded Investment				$ 26
State and Other Political Subdivision Loans [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract				2
Pre-Modification Outstanding Recorded Investment				$ 3,902
Post-Modification Outstanding Recorded Investment				$ 3,872
Other Commercial Loans [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts | Contract			2
Pre-Modification Outstanding Recorded Investment			$ 4,929
Post-Modification Outstanding Recorded Investment			$ 4,929