Disclosures About Fair Value of Assets and Liabilities - Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Assets:
Investment securities available for sale	$ 2,164,197	$ 2,344,551
Investment securities held to maturity	2,145,994	2,202,503
Loans held for sale	3,938	11,187
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash and cash equivalents	148,277	167,146
Interest-bearing deposits	395,262	474,154
Investment securities available for sale	1,959	999
Investment securities held to maturity	0	0
Loans held for sale	0	0
Loans, net	0	0
Federal Home Loan Bank stock	0	0
Interest rate swap asset	0	0
Interest receivable	0	0
Liabilities:
Deposits	12,250,450	12,038,992
Borrowings:
Securities sold under repurchase agreements	0	0
Federal Home Loan Bank advances	0	0
Subordinated debentures and other borrowings	0	0
Interest rate swap liability	0	0
Interest payable	0	0
Significant Other Observable Inputs (Level 2)
Assets:
Cash and cash equivalents	0	0
Interest-bearing deposits	0	0
Investment securities available for sale	2,153,326	2,338,061
Investment securities held to maturity	2,132,711	2,188,600
Loans held for sale	3,938	11,187
Loans, net	0	0
Federal Home Loan Bank stock	26,422	28,736
Interest rate swap asset	34,995	41,133
Interest receivable	56,081	57,187
Liabilities:
Deposits	646,951	690,089
Borrowings:
Securities sold under repurchase agreements	169,679	181,572
Federal Home Loan Bank advances	307,288	337,005
Subordinated debentures and other borrowings	111,691	107,892
Interest rate swap liability	35,287	41,968
Interest payable	3,589	2,762
Significant Unobservable Inputs (Level 3)
Assets:
Cash and cash equivalents	0	0
Interest-bearing deposits	0	0
Investment securities available for sale	8,912	5,491
Investment securities held to maturity	13,283	13,903
Loans held for sale	0	0
Loans, net	8,969,530	9,068,319
Federal Home Loan Bank stock	0	0
Interest rate swap asset	0	0
Interest receivable	0	0
Liabilities:
Deposits	0	0
Borrowings:
Securities sold under repurchase agreements	0	0
Federal Home Loan Bank advances	0	0
Subordinated debentures and other borrowings	0	0
Interest rate swap liability	0	0
Interest payable	0	0
Carrying Amount
Assets:
Cash and cash equivalents	148,277	167,146
Interest-bearing deposits	395,262	474,154
Investment securities available for sale	2,164,197	2,344,551
Investment securities held to maturity	2,325,066	2,179,802
Loans held for sale	3,938	11,187
Loans, net	9,160,257	9,046,464
Federal Home Loan Bank stock	26,422	28,736
Interest rate swap asset	34,995	41,133
Interest receivable	56,081	57,187
Liabilities:
Deposits	12,905,953	12,732,577
Borrowings:
Securities sold under repurchase agreements	169,697	181,577
Federal Home Loan Bank advances	308,960	334,055
Subordinated debentures and other borrowings	118,677	118,618
Interest rate swap liability	35,287	41,968
Interest payable	$ 3,589	$ 2,762

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Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Fair value portion of borrowing from Federal Home Loan Bank (FHLBank).

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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Fair value portion of securities that an entity sells and agrees to repurchase at a specified date for a specified price.

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