Fair Value - Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($)	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022
Assets
Securities available-for-sale	$ 273,043,000		$ 442,636,000
Securities held-to-maturity	527,438,000		564,127,000
FHLB stock, FRB stock, and other investments	32,549,000		32,540,000
Liabilities
Subordinated debt	39,577,000		39,502,000
Allowance for credit losses on loans	47,954,000	$ 47,888,000	47,958,000	$ 47,803,000	$ 47,273,000	$ 47,512,000
Carrying Amounts
Assets
Cash and cash equivalents	648,260,000		408,129,000
Securities available-for-sale	273,043,000		442,636,000
Securities held-to-maturity	621,178,000		650,565,000
Loans (including loans held-for-sale)	3,381,692,000		3,352,583,000
FHLB stock, FRB stock, and other investments	32,549,000		32,540,000
Accrued interest receivable	14,441,000		14,959,000
I/O strips receivables	101,000		117,000
Liabilities
Time deposits	492,780,000		469,472,000
Other deposits	3,951,830,000		3,908,986,000
Subordinated debt	39,577,000		39,502,000
Accrued interest payable	5,176,000		4,688,000
Balance
Assets
Cash and cash equivalents	648,260,000		408,129,000
Securities available-for-sale	273,043,000		442,636,000
Securities held-to-maturity	527,438,000		564,127,000
Loans (including loans held-for-sale)	3,178,803,000		3,174,717,000
Accrued interest receivable	14,441,000		14,959,000
I/O strips receivables	101,000		117,000
Liabilities
Time deposits	494,689,000		471,693,000
Other deposits	3,951,830,000		3,908,986,000
Subordinated debt	32,377,000		31,902,000
Accrued interest payable	5,176,000		4,698,000
Balance | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Cash and cash equivalents	648,260,000		408,129,000
Securities available-for-sale	218,682,000		382,369,000
Accrued interest receivable	774,000		1,255,000
Balance | Significant Other Observable Inputs (Level 2)
Assets
Securities available-for-sale	54,361,000		60,267,000
Securities held-to-maturity	527,438,000		564,127,000
Loans (including loans held-for-sale)	1,899,000		2,205,000
Accrued interest receivable	1,806,000		1,764,000
I/O strips receivables	101,000		117,000
Liabilities
Time deposits	494,689,000		471,693,000
Other deposits	3,951,830,000		3,908,986,000
Subordinated debt	32,377,000		31,902,000
Accrued interest payable	5,176,000		4,698,000
Balance | Significant Unobservable Inputs (Level 3)
Assets
Loans (including loans held-for-sale)	3,176,904,000		3,172,512,000
Accrued interest receivable	$ 11,861,000		$ 11,940,000