Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Change in Allowance for Loan Losses (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	$ 99,457,000	$ 117,306,000
Loans charged-off	(2,242,000)	(1,245,000)
Recoveries	2,379,000	3,631,000
Net (charge-offs) recoveries	137,000	2,386,000
PCL	(860,000)	(10,501,000)
Balance at end of period	98,734,000
Commercial and Industrial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
PCL		4,100
Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	99,457,000	117,306,000
Loans charged-off	(2,242,000)	(1,245,000)
Recoveries	2,379,000	3,631,000
PCL	(860,000)	(10,501,000)
Balance at end of period	98,734,000	109,191,000
Allowance for Credit Losses, ACL [Member] | Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	6,079,000	6,854,000
Loans charged-off	(28,000)
Recoveries	843,000	766,000
PCL	457,000	(2,562,000)
Balance at end of period	7,351,000	5,058,000
Allowance for Credit Losses, ACL [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	10,310,000	9,928,000
Loans charged-off	(13,000)	(26,000)
Recoveries	89,000	71,000
PCL	(519,000)	(1,306,000)
Balance at end of period	9,867,000	8,667,000
Allowance for Credit Losses, ACL [Member] | Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	2,706,000	5,143,000
Loans charged-off
Recoveries	6,000	100,000
PCL	2,916,000	(1,490,000)
Balance at end of period	5,628,000	3,753,000
Allowance for Credit Losses, ACL [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	37,912,000	48,523,000
Loans charged-off
Recoveries	27,000	30,000
PCL	(5,909,000)	2,115,000
Balance at end of period	32,030,000	46,438,000
Allowance for Credit Losses, ACL [Member] | Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	4,713,000	7,382,000
Loans charged-off
Recoveries	3,000	6,000
PCL	(1,076,000)	(1,618,000)
Balance at end of period	3,640,000	5,770,000
Allowance for Credit Losses, ACL [Member] | Commercial and Industrial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	18,939,000	14,851,000
Loans charged-off	(285,000)	(23,000)
Recoveries	100,000	1,287,000
PCL	(3,803,000)	4,051,000
Balance at end of period	14,951,000	20,166,000
Allowance for Credit Losses, ACL [Member] | Other Construction [Member] | Other Loans Secured by Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	5,968,000	8,158,000
Loans charged-off
Recoveries	3,000	1,000
PCL	7,976,000	(3,035,000)
Balance at end of period	13,947,000	5,124,000
Allowance for Credit Losses, ACL [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	4,774,000	5,838,000
Loans charged-off	(579,000)	(442,000)
Recoveries	379,000	362,000
PCL	298,000	(1,008,000)
Balance at end of period	4,872,000	4,750,000
Allowance for Credit Losses, ACL [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	2,708,000	3,190,000
Loans charged-off
Recoveries
PCL	(337,000)	(175,000)
Balance at end of period	2,371,000	3,015,000
Allowance for Credit Losses, ACL [Member] | Other Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	5,348,000	7,439,000
Loans charged-off	(1,337,000)	(754,000)
Recoveries	929,000	1,008,000
PCL	(863,000)	1,243,000
Balance at end of period	$ 4,077,000	$ 6,450,000