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	12 Months Ended
	Dec. 31, 2019 USD ($) Contract	Dec. 31, 2018 USD ($) Contract	Dec. 31, 2017 USD ($) Contract
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	30	52	33
Pre-Modification Outstanding Recorded Investment	$ 15,994	$ 30,878	$ 15,637
Post-Modification Outstanding Recorded Investment	$ 15,877	$ 29,328	$ 15,630
Secured by 1-4 Family Residential Properties [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	19	23	22
Pre-Modification Outstanding Recorded Investment	$ 1,742	$ 2,102	$ 1,478
Post-Modification Outstanding Recorded Investment	$ 1,738	$ 1,660	$ 1,487
Secured by Nonfarm, Nonresidential Properties [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	1	2	1
Pre-Modification Outstanding Recorded Investment	$ 5,055	$ 1,780	$ 426
Post-Modification Outstanding Recorded Investment	$ 5,055	$ 1,780	$ 426
Commercial and Industrial Loans [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	8	23	8
Pre-Modification Outstanding Recorded Investment	$ 9,167	$ 26,970	$ 12,836
Post-Modification Outstanding Recorded Investment	$ 9,054	$ 25,862	$ 12,836
Consumer Loans [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	2	3
Pre-Modification Outstanding Recorded Investment	$ 30	$ 4
Post-Modification Outstanding Recorded Investment	$ 30	$ 4
Construction, Land Development and Other Land [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract		1	1
Pre-Modification Outstanding Recorded Investment		$ 22	$ 341
Post-Modification Outstanding Recorded Investment		$ 22	$ 325
Other Loans [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract			1
Pre-Modification Outstanding Recorded Investment			$ 556
Post-Modification Outstanding Recorded Investment			$ 556