Allowance for Credit Losses - Summary of Total Non Purchased and Purchased Loans (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 11,000,796	$ 9,693,463
Unearned income	(3,492)	(3,825)
Loans, net of unearned income	10,997,304	9,689,638
Allowance for credit losses	(145,387)	(52,162)
Loans, net	10,851,917	9,637,476
Cumulative Effect, Period Of Adoption, Adjusted Balance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income		9,689,638
Allowance for credit losses		(94,646)
Commercial, financial, agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	2,641,598	1,367,972
Loans, net of unearned income	2,641,598	1,367,972
Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	84,271	85,700
Loans, net of unearned income	80,779
Real estate – construction:
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	791,108	826,483
Loans, net of unearned income	791,108	826,483
Real estate – construction: \| Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	295,931	289,050
Real estate – construction: \| Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	495,177	537,433
Real estate – 1-4 family mortgage:
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	2,788,513	2,866,613
Loans, net of unearned income	2,788,513	2,866,613
Real estate – 1-4 family mortgage: \| Primary
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	1,756,253	1,781,948
Real estate – 1-4 family mortgage: \| Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	543,468	573,540
Real estate – 1-4 family mortgage: \| Rental/investment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	318,803	335,100
Real estate – 1-4 family mortgage: \| Land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	169,989	176,025
Real estate – commercial mortgage:
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	4,410,753	4,244,265
Loans, net of unearned income	4,410,753	4,244,265
Real estate – commercial mortgage: \| Land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	155,766	156,089
Real estate – commercial mortgage: \| Owner-occupied
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	1,660,674	1,637,281
Real estate – commercial mortgage: \| Non-owner occupied
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	2,594,313	2,450,895
Installment loans to individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	284,553	302,430
Loans, net of unearned income	$ 284,553	$ 384,305

Financing Receivable, before Allowance for Credit Loss, Net of Unearned Income

No definition available.

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- Definition

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.

+ References

No definition available.

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- Definition

Amount of fee received for commitment to originate or purchase financing receivable where likelihood of commitment being exercised is remote. Excludes financing receivable covered under loss sharing agreement.

+ References

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-Publisher FASB
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- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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- Definition

Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

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Amount, before allowance for credit loss, of financing receivable.

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