Disclosures About Fair Value of Assets and Liabilities - Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Assets:
Investment securities available for sale	$ 1,815,775	$ 1,790,025
Investment securities held to maturity	920,178	827,566
Loans held for sale	5,039	9,037
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash and cash equivalents	127,731	177,201
Interest-bearing time deposits	132,944	118,263
Investment securities available for sale	0	0
Investment securities held to maturity	0	0
Loans held for sale	0	0
Loans	0	0
Federal Home Loan Bank stock	0	0
Interest rate swap asset	0	0
Interest receivable	0	0
Liabilities:
Deposits	8,256,022	8,146,745
Borrowings:
Federal funds purchased	0	0
Securities sold under repurchase agreements	0	0
Federal Home Loan Bank advances	0	0
Subordinated debentures and term loans	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 time deposits	0	0
Investment securities available for sale	1,813,246	1,787,132
Investment securities held to maturity	895,075	799,884
Loans held for sale	5,039	9,037
Loans	0	0
Federal Home Loan Bank stock	28,736	28,736
Interest rate swap asset	78,762	27,855
Interest receivable	47,489	48,901
Liabilities:
Deposits	1,610,891	1,675,202
Borrowings:
Federal funds purchased	47,000	55,000
Securities sold under repurchase agreements	183,350	187,801
Federal Home Loan Bank advances	493,455	352,581
Subordinated debentures and term loans	124,167	123,571
Interest rate swap liability	81,395	29,299
Interest payable	7,746	6,754
Significant Unobservable Inputs (Level 3)
Assets:
Cash and cash equivalents	0	0
Interest-bearing time deposits	0	0
Investment securities available for sale	2,529	2,893
Investment securities held to maturity	25,103	27,682
Loans held for sale	0	0
Loans	8,612,153	8,335,340
Federal Home Loan Bank stock	0	0
Interest rate swap asset	0	0
Interest receivable	0	0
Liabilities:
Deposits	0	0
Borrowings:
Federal funds purchased	0	0
Securities sold under repurchase agreements	0	0
Federal Home Loan Bank advances	0	0
Subordinated debentures and term loans	0	0
Interest rate swap liability	0	0
Interest payable	0	0
Carrying Amount
Assets:
Cash and cash equivalents	127,731	177,201
Interest-bearing time deposits	132,944	118,263
Investment securities available for sale	1,815,775	1,790,025
Investment securities held to maturity	882,179	806,038
Loans held for sale	5,039	9,037
Loans	8,507,395	8,379,026
Federal Home Loan Bank stock	28,736	28,736
Interest rate swap asset	78,762	27,855
Interest receivable	47,489	48,901
Liabilities:
Deposits	9,870,484	9,839,956
Borrowings:
Federal funds purchased	47,000	55,000
Securities sold under repurchase agreements	183,317	187,946
Federal Home Loan Bank advances	480,995	351,072
Subordinated debentures and term loans	128,741	138,685
Interest rate swap liability	81,395	29,299
Interest payable	$ 7,746	$ 6,754

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Interest Bearing Deposits with Banks, Fair Value Disclosure

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Amount 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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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 30
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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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Fair value portion of short term borrowing where a bank borrows, at the federal funds rate, from another bank.

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

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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Fair value as of the balance sheet date of interest rate derivative assets, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as assets.

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Fair value portion of investments in Federal Home Loan Bank (FHLBank) stock.

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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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The face amount of loans that will be sold to other entities.

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Fair value portion of other liabilities.

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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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