Fair Value Measurements - Schedule of Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Assets
Federal funds sold	$ 11,343	$ 3,740
Interest-bearing deposits with other banks	696,453	709,897
Investment securities available-for-sale	1,445,034	1,506,388
Total investment securities held-to-maturity	878,159	901,582
Federal Reserve and Federal Home Loan Bank stock	54,678	25,748
Bank owned life insurance	113,624	112,921
Liabilities
Interest-bearing deposits	1,207,566	997,448
Customer repurchase agreements	37,059	30,587
Carrying Value
Assets
Cash and due from banks	10,076	9,047
Federal funds sold	11,343	3,740
Interest-bearing deposits with other banks	696,453	709,897
Investment securities available-for-sale	1,445,034	1,506,388
Total investment securities held-to-maturity	1,000,732	1,015,737
Federal Reserve and Federal Home Loan Bank stock	54,678	25,748
Loans	7,982,702	7,968,695
Bank owned life insurance	113,624	112,921
Annuity investment	12,948	13,112
Accrued interest receivable	54,074	53,337
Liabilities
Noninterest-bearing deposits	1,835,524	2,279,081
Interest-bearing deposits	4,442,957	4,311,491
Time deposits	2,222,958	2,217,467
Customer repurchase agreements	37,059	30,587
Borrowings	1,669,948	1,369,918
Accrued interest payable	20,978	57,395
Carrying Value | Credit Risk Participation Agreements
Assets
Derivative asset		3
Carrying Value | Interest rate product
Assets
Derivative asset	34,147	30,662
Liabilities
Derivative liability	33,646	30,555
Fair Value
Assets
Cash and due from banks	10,076	9,047
Federal funds sold	11,343	3,740
Interest-bearing deposits with other banks	696,453	709,897
Investment securities available-for-sale	1,445,034	1,506,388
Total investment securities held-to-maturity	878,159	901,582
Loans	7,596,097	7,720,241
Bank owned life insurance	113,624	112,921
Annuity investment	12,948	13,112
Accrued interest receivable	54,074	53,337
Liabilities
Noninterest-bearing deposits	1,835,524	2,279,081
Interest-bearing deposits	4,442,957	4,311,491
Time deposits	2,217,742	2,217,795
Customer repurchase agreements	37,059	30,587
Borrowings	1,669,043	1,368,621
Accrued interest payable	20,978	57,395
Fair Value | Credit Risk Participation Agreements
Assets
Derivative asset		3
Fair Value | Interest rate product
Assets
Derivative asset	34,147	30,662
Liabilities
Derivative liability	33,646	30,555
Fair Value | ​Quoted Prices (Level 1)
Assets
Cash and due from banks	10,076	9,047
Federal funds sold	0	0
Interest-bearing deposits with other banks	0	0
Investment securities available-for-sale	0	0
Total investment securities held-to-maturity	0	0
Federal Reserve and Federal Home Loan Bank stock	0	0
Loans	0	0
Bank owned life insurance	0	0
Annuity investment	0	0
Accrued interest receivable	54,074	53,337
Liabilities
Noninterest-bearing deposits	0	0
Interest-bearing deposits	0	0
Time deposits	0	0
Customer repurchase agreements	0	0
Borrowings	0	0
Accrued interest payable	20,978	57,395
Fair Value | ​Quoted Prices (Level 1) | Credit Risk Participation Agreements
Assets
Derivative asset		0
Fair Value | ​Quoted Prices (Level 1) | Interest rate product
Assets
Derivative asset	0	0
Liabilities
Derivative liability	0	0
Fair Value | Significant Other Observable Inputs (Level 2)
Assets
Cash and due from banks	0	0
Federal funds sold	11,343	3,740
Interest-bearing deposits with other banks	696,453	709,897
Investment securities available-for-sale	1,445,034	1,506,388
Total investment securities held-to-maturity	878,159	901,582
Federal Reserve and Federal Home Loan Bank stock	0	0
Loans	0	0
Bank owned life insurance	113,624	112,921
Annuity investment	12,948	13,112
Accrued interest receivable	0	0
Liabilities
Noninterest-bearing deposits	1,835,524	2,279,081
Interest-bearing deposits	4,442,957	4,311,491
Time deposits	2,217,742	2,217,795
Customer repurchase agreements	37,059	30,587
Borrowings	1,669,043	1,368,621
Accrued interest payable	0	0
Fair Value | Significant Other Observable Inputs (Level 2) | Credit Risk Participation Agreements
Assets
Derivative asset		3
Fair Value | Significant Other Observable Inputs (Level 2) | Interest rate product
Assets
Derivative asset	34,147	30,662
Liabilities
Derivative liability	33,646	30,555
Fair Value | Significant Other Unobservable Inputs (Level 3)
Assets
Cash and due from banks	0	0
Federal funds sold	0	0
Interest-bearing deposits with other banks	0	0
Investment securities available-for-sale	0	0
Total investment securities held-to-maturity	0	0
Federal Reserve and Federal Home Loan Bank stock	0	0
Loans	7,596,097	7,720,241
Bank owned life insurance	0	0
Annuity investment	0	0
Accrued interest receivable	0	0
Liabilities
Noninterest-bearing deposits	0	0
Interest-bearing deposits	0	0
Time deposits	0	0
Customer repurchase agreements	0	0
Borrowings	0	0
Accrued interest payable	0	0
Fair Value | Significant Other Unobservable Inputs (Level 3) | Credit Risk Participation Agreements
Assets
Derivative asset		0
Fair Value | Significant Other Unobservable Inputs (Level 3) | Interest rate product
Assets
Derivative asset	0	0
Liabilities
Derivative liability	$ 0	$ 0