Fair Value Measurements - Estimated Fair Values and Related Carrying Amounts of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities, net	$ 3,049,282	$ 3,135,370
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	603,303	614,092
Interest bearing balances due from banks - time	100	100
Held-to-maturity securities, net	3,707,258	3,726,288
Interest receivable	122,781	122,430
Federal funds purchased and securities sold under agreements to repurchase	58,760	67,969
Other borrowings	871,874	972,366
Subordinated notes and debentures	366,179	366,141
Interest payable	39,234	35,618
Carrying Amount \| Noninterest bearing transaction accounts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	4,697,539	4,800,880
Carrying Amount \| Interest bearing transaction accounts and savings deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	11,071,762	10,997,425
Carrying Amount \| Time deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	6,583,703	6,446,673
Carrying Amount \| Legacy Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	16,774,393	16,620,439
Fair Value Measurements
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	603,303	614,092
Interest bearing balances due from banks - time	100	100
Held-to-maturity securities, net	3,049,282	3,135,370
Interest receivable	122,781	122,430
Federal funds purchased and securities sold under agreements to repurchase	58,760	67,969
Other borrowings	869,691	970,846
Subordinated notes and debentures	355,921	349,424
Interest payable	39,234	35,618
Fair Value Measurements \| Noninterest bearing transaction accounts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	4,697,539	4,800,880
Fair Value Measurements \| Interest bearing transaction accounts and savings deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	11,071,762	10,997,425
Fair Value Measurements \| Time deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	6,549,191	6,414,222
Fair Value Measurements \| Legacy Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	15,786,397	15,734,766
Fair Value Measurements \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	603,303	614,092
Interest bearing balances due from banks - time	0	0
Held-to-maturity securities, net	0	0
Interest receivable	0	0
Federal funds purchased and securities sold under agreements to repurchase	0	0
Other borrowings	0	0
Subordinated notes and debentures	0	0
Interest payable	0	0
Fair Value Measurements \| Level 1 \| Noninterest bearing transaction accounts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	0	0
Fair Value Measurements \| Level 1 \| Interest bearing transaction accounts and savings deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	0	0
Fair Value Measurements \| Level 1 \| Time deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	0	0
Fair Value Measurements \| Level 1 \| Legacy Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	0	0
Fair Value Measurements \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	0
Interest bearing balances due from banks - time	100	100
Held-to-maturity securities, net	3,049,282	3,135,370
Interest receivable	122,781	122,430
Federal funds purchased and securities sold under agreements to repurchase	58,760	67,969
Other borrowings	869,691	970,846
Subordinated notes and debentures	355,921	349,424
Interest payable	39,234	35,618
Fair Value Measurements \| Level 2 \| Noninterest bearing transaction accounts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	4,697,539	4,800,880
Fair Value Measurements \| Level 2 \| Interest bearing transaction accounts and savings deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	11,071,762	10,997,425
Fair Value Measurements \| Level 2 \| Time deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	0	0
Fair Value Measurements \| Level 2 \| Legacy Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	0	0
Fair Value Measurements \| Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	0
Interest bearing balances due from banks - time	0	0
Held-to-maturity securities, net	0	0
Interest receivable	0	0
Federal funds purchased and securities sold under agreements to repurchase	0	0
Other borrowings	0	0
Subordinated notes and debentures	0	0
Interest payable	0	0
Fair Value Measurements \| Level 3 \| Noninterest bearing transaction accounts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	0	0
Fair Value Measurements \| Level 3 \| Interest bearing transaction accounts and savings deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	0	0
Fair Value Measurements \| Level 3 \| Time deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deposits	6,549,191	6,414,222
Fair Value Measurements \| Level 3 \| Legacy Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	$ 15,786,397	$ 15,734,766

Represents the fair value portion of interest bearing balances due from banks - time.

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- Definition

Fair value portion of interest payable on debt, including, but not limited to, trade payables.

+ References

No definition available.

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The fair value of accrued interest receivable.

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- Definition

The fair value portion of the aggregate of other miscellaneous borrowings owed by the reporting entity as of the balance sheet date.

+ References

No definition available.

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- Definition

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.

+ References

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- Definition

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.

+ References

No definition available.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Fair value of subordinated debt obligations including, but not limited to, subordinated loan, subordinated bond, subordinated debenture or junior debt.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
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- Definition

Fair value portion of short term borrowing where a bank borrows, at the federal funds rate, from another bank and securities that an entity sells and agrees to repurchase at a specified date for a specified price.

+ References

No definition available.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(1))
-Publisher FASB
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-Topic 320
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Publisher FASB
-URI https://asc.fasb.org//310-10/tableOfContent

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