Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Impaired Financing Receivables (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	$ 47,289	$ 62,921
Total LHFI With No Related Allowance Recorded	23,550	25,553
Total LHFI With an Allowance Recorded	17,667	30,282
Total LHFI Carrying Amount	41,217	55,835
Related Allowance	5,459	6,354
Average Recorded Investment	48,525	46,920
Commercial and Industrial Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	27,178	37,786
Total LHFI With No Related Allowance Recorded	19,374	12,893
Total LHFI With an Allowance Recorded	4,084	17,824
Total LHFI Carrying Amount	23,458	30,717
Related Allowance	707	4,334
Average Recorded Investment	27,088	26,725
Consumer Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	22	2
Total LHFI With No Related Allowance Recorded	0	0
Total LHFI With an Allowance Recorded	21	2
Total LHFI Carrying Amount	21	2
Related Allowance	0	0
Average Recorded Investment	11	6
State and Other Political Subdivision Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	4,079	8,688
Total LHFI With No Related Allowance Recorded	0	4,079
Total LHFI With an Allowance Recorded	4,079	4,516
Total LHFI Carrying Amount	4,079	8,595
Related Allowance	1,809	516
Average Recorded Investment	6,337	4,297
Other Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	1,207	1,418
Total LHFI With No Related Allowance Recorded	0	230
Total LHFI With an Allowance Recorded	784	1,052
Total LHFI Carrying Amount	784	1,282
Related Allowance	553	1,052
Average Recorded Investment	1,033	804
Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	926	1,794
Total LHFI With No Related Allowance Recorded	610	1,528
Total LHFI With an Allowance Recorded	16	24
Total LHFI Carrying Amount	626	1,552
Related Allowance	0	0
Average Recorded Investment	1,089	1,738
Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	6,513	4,951
Total LHFI With No Related Allowance Recorded	2,104	95
Total LHFI With an Allowance Recorded	3,360	3,868
Total LHFI Carrying Amount	5,464	3,963
Related Allowance	35	39
Average Recorded Investment	4,713	4,328
Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	7,295	8,282
Total LHFI With No Related Allowance Recorded	1,462	6,728
Total LHFI With an Allowance Recorded	5,255	2,748
Total LHFI Carrying Amount	6,717	9,476
Related Allowance	2,355	413
Average Recorded Investment	8,096	8,898
Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	69	0
Total LHFI With No Related Allowance Recorded	0	0
Total LHFI With an Allowance Recorded	68	248
Total LHFI Carrying Amount	68	248
Related Allowance	0	0
Average Recorded Investment	$ 158	$ 124