Fair Value Measurements - Other Real Estate Owned and Repossessed Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023		Mar. 31, 2022	Dec. 31, 2022		Dec. 31, 2021
Fair Value Measurements
Loans held for investment	$ 1,542,074			$ 1,521,252
Allowance for credit losses on loans	21,979	[1]	$ 14,279	15,588	[1]	$ 16,903
Commercial, financial, & agricultural
Fair Value Measurements
Loans held for investment	227,992			244,549
Allowance for credit losses on loans	1,921		2,830	$ 2,735		$ 2,717
Nonrecurring | Fair value
Fair Value Measurements
Other real estate and repossessed assets	8,247		9,758
Nonrecurring | Fair value | Collateral dependent impaired loans
Fair Value Measurements
Loans held for investment	18,364		15,365
Allowance for credit losses on loans	100
Nonrecurring | Fair value | Commercial, financial, & agricultural | Collateral dependent impaired loans
Fair Value Measurements
Loans held for investment	50
Nonrecurring | Fair value | Real estate mortgage - residential | Mortgage | Collateral dependent impaired loans
Fair Value Measurements
Loans held for investment	86
Nonrecurring | Fair value | Real estate construction − commercial & Real estate mortgage − commercial | Mortgage | Collateral dependent impaired loans
Fair Value Measurements
Loans held for investment	18,228		15,365
Nonrecurring | Total Gains (Losses)
Fair Value Measurements
Gains (losses) on other real estate and repossessed assets	9		(45)
Nonrecurring | Total Gains (Losses) | Collateral dependent impaired loans
Fair Value Measurements
Gains (losses) on impaired loans	(5)		(23)
Nonrecurring | Total Gains (Losses) | Commercial, financial, & agricultural | Collateral dependent impaired loans
Fair Value Measurements
Gains (losses) on impaired loans	0
Nonrecurring | Total Gains (Losses) | Real estate mortgage - residential | Mortgage | Collateral dependent impaired loans
Fair Value Measurements
Gains (losses) on impaired loans	0
Nonrecurring | Total Gains (Losses) | Real estate construction − commercial & Real estate mortgage − commercial | Mortgage | Collateral dependent impaired loans
Fair Value Measurements
Gains (losses) on impaired loans	(5)		(23)
Nonrecurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value
Fair Value Measurements
Other real estate and repossessed assets	0		0
Nonrecurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value | Collateral dependent impaired loans
Fair Value Measurements
Loans held for investment	0		0
Nonrecurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value | Commercial, financial, & agricultural | Collateral dependent impaired loans
Fair Value Measurements
Loans held for investment	0
Nonrecurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value | Real estate mortgage - residential | Mortgage | Collateral dependent impaired loans
Fair Value Measurements
Loans held for investment	0
Nonrecurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value | Real estate construction − commercial & Real estate mortgage − commercial | Mortgage | Collateral dependent impaired loans
Fair Value Measurements
Loans held for investment	0		0
Nonrecurring | Other Observable Inputs (Level 2) | Fair value
Fair Value Measurements
Other real estate and repossessed assets	0		0
Nonrecurring | Other Observable Inputs (Level 2) | Fair value | Collateral dependent impaired loans
Fair Value Measurements
Loans held for investment	0		0
Nonrecurring | Other Observable Inputs (Level 2) | Fair value | Commercial, financial, & agricultural | Collateral dependent impaired loans
Fair Value Measurements
Loans held for investment	0
Nonrecurring | Other Observable Inputs (Level 2) | Fair value | Real estate mortgage - residential | Mortgage | Collateral dependent impaired loans
Fair Value Measurements
Loans held for investment	0
Nonrecurring | Other Observable Inputs (Level 2) | Fair value | Real estate construction − commercial & Real estate mortgage − commercial | Mortgage | Collateral dependent impaired loans
Fair Value Measurements
Loans held for investment	0		0
Nonrecurring | Significant Unobservable Inputs (Level 3) | Fair value
Fair Value Measurements
Other real estate and repossessed assets	8,247		9,758
Nonrecurring | Significant Unobservable Inputs (Level 3) | Fair value | Collateral dependent impaired loans
Fair Value Measurements
Loans held for investment	18,364		15,365
Nonrecurring | Significant Unobservable Inputs (Level 3) | Fair value | Commercial, financial, & agricultural | Collateral dependent impaired loans
Fair Value Measurements
Loans held for investment	50
Nonrecurring | Significant Unobservable Inputs (Level 3) | Fair value | Real estate mortgage - residential | Mortgage | Collateral dependent impaired loans
Fair Value Measurements
Loans held for investment	86
Nonrecurring | Significant Unobservable Inputs (Level 3) | Fair value | Real estate construction − commercial & Real estate mortgage − commercial | Mortgage | Collateral dependent impaired loans
Fair Value Measurements
Loans held for investment	$ 18,228		$ 15,365

[1] March 31, 2023 amounts include the impacts of the January 1, 2023 adoption of ASU 2013-13. See Note 2 for details.See accompanying notes to the consolidated financial statements (unaudited)