Fair Value Measurements - Other Real Estate Owned and Repossessed Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Fair Value Measurements
Total of collateral dependent impaired loans	$ 1,495,178		$ 1,515,403
Nonrecurring | Fair value
Fair Value Measurements
Other real estate and repossessed assets	1,937	$ 8,247
Nonrecurring | Fair value | Collateral dependent impaired loans
Fair Value Measurements
Total of collateral dependent impaired loans	3,787	18,364
Nonrecurring | Fair value | Real estate mortgage − residential | Collateral dependent impaired loans
Fair Value Measurements
Total of collateral dependent impaired loans	21	86
Nonrecurring | Fair value | Real estate mortgage − commercial | Collateral dependent impaired loans
Fair Value Measurements
Total of collateral dependent impaired loans	3,163	18,228
Nonrecurring | Fair value | Commercial, Financial, and Agricultural | Collateral dependent impaired loans
Fair Value Measurements
Total of collateral dependent impaired loans	343	50
Nonrecurring | Fair value | Real estate construction − residential | Collateral dependent impaired loans
Fair Value Measurements
Total of collateral dependent impaired loans	260
Nonrecurring | Total Gains (Losses)
Fair Value Measurements
Gains (losses) on other real estate and repossessed assets	34	9
Nonrecurring | Total Gains (Losses) | Collateral dependent impaired loans
Fair Value Measurements
Gains (losses) on impaired loans	(23)	(5)
Nonrecurring | Total Gains (Losses) | Real estate mortgage − residential | Collateral dependent impaired loans
Fair Value Measurements
Gains (losses) on impaired loans	0	0
Nonrecurring | Total Gains (Losses) | Real estate mortgage − commercial | Collateral dependent impaired loans
Fair Value Measurements
Gains (losses) on impaired loans	(23)	(5)
Nonrecurring | Total Gains (Losses) | Commercial, Financial, and Agricultural | Collateral dependent impaired loans
Fair Value Measurements
Gains (losses) on impaired loans	0	0
Nonrecurring | Total Gains (Losses) | Real estate construction − residential | Collateral dependent impaired loans
Fair Value Measurements
Gains (losses) on impaired loans	0
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
Total of collateral dependent impaired loans	0	0
Nonrecurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value | Real estate mortgage − residential | Collateral dependent impaired loans
Fair Value Measurements
Total of collateral dependent impaired loans	0	0
Nonrecurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value | Real estate mortgage − commercial | Collateral dependent impaired loans
Fair Value Measurements
Total of collateral dependent impaired loans	0	0
Nonrecurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value | Commercial, Financial, and Agricultural | Collateral dependent impaired loans
Fair Value Measurements
Total of collateral dependent impaired loans	0	0
Nonrecurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value | Real estate construction − residential | Collateral dependent impaired loans
Fair Value Measurements
Total of collateral dependent impaired loans	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
Total of collateral dependent impaired loans	0	0
Nonrecurring | Other Observable Inputs (Level 2) | Fair value | Real estate mortgage − residential | Collateral dependent impaired loans
Fair Value Measurements
Total of collateral dependent impaired loans	0	0
Nonrecurring | Other Observable Inputs (Level 2) | Fair value | Real estate mortgage − commercial | Collateral dependent impaired loans
Fair Value Measurements
Total of collateral dependent impaired loans	0	0
Nonrecurring | Other Observable Inputs (Level 2) | Fair value | Commercial, Financial, and Agricultural | Collateral dependent impaired loans
Fair Value Measurements
Total of collateral dependent impaired loans	0	0
Nonrecurring | Other Observable Inputs (Level 2) | Fair value | Real estate construction − residential | Collateral dependent impaired loans
Fair Value Measurements
Total of collateral dependent impaired loans	0
Nonrecurring | Significant Unobservable Inputs (Level 3) | Fair value
Fair Value Measurements
Other real estate and repossessed assets	1,937	8,247
Nonrecurring | Significant Unobservable Inputs (Level 3) | Fair value | Collateral dependent impaired loans
Fair Value Measurements
Total of collateral dependent impaired loans	3,787	18,364
Nonrecurring | Significant Unobservable Inputs (Level 3) | Fair value | Real estate mortgage − residential | Collateral dependent impaired loans
Fair Value Measurements
Total of collateral dependent impaired loans	21	86
Nonrecurring | Significant Unobservable Inputs (Level 3) | Fair value | Real estate mortgage − commercial | Collateral dependent impaired loans
Fair Value Measurements
Total of collateral dependent impaired loans	3,163	18,228
Nonrecurring | Significant Unobservable Inputs (Level 3) | Fair value | Commercial, Financial, and Agricultural | Collateral dependent impaired loans
Fair Value Measurements
Total of collateral dependent impaired loans	343	$ 50
Nonrecurring | Significant Unobservable Inputs (Level 3) | Fair value | Real estate construction − residential | Collateral dependent impaired loans
Fair Value Measurements
Total of collateral dependent impaired loans	$ 260