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Loans and Allowance for Credit Losses - Modifications Subsequent Default (Detail) $ in Thousands | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2025 USD ($) Contract | Dec. 31, 2024 USD ($) Contract
Financing Receivable, Modified, Subsequent Default [Line Items] |  |
Financing Receivable, Troubled Debt Restructuring, Subsequent Default | $ | $ 16,486 | $ 179
Financing Receivable, Modified, Subsequent Default, Number of contracts | Contract | 3,000 | 2,000
Commercial, financial, agricultural and other [Member] |  |
Financing Receivable, Modified, Subsequent Default [Line Items] |  |
Financing Receivable, Troubled Debt Restructuring, Subsequent Default | $ | $ 16,196 | $ 0
Financing Receivable, Modified, Subsequent Default, Number of contracts | Contract | 2,000 | 0
Commercial, financial, agricultural and other [Member] | Equipment Finance |  |
Financing Receivable, Modified, Subsequent Default [Line Items] |  |
Financing Receivable, Troubled Debt Restructuring, Subsequent Default | $ | $ 181 | $ 0
Financing Receivable, Modified, Subsequent Default, Number of contracts | Contract | 1,000 | 0
Commercial, financial, agricultural and other [Member] | Time and Demand Loans Other |  |
Financing Receivable, Modified, Subsequent Default [Line Items] |  |
Financing Receivable, Troubled Debt Restructuring, Subsequent Default | $ | $ 16,015 | $ 0
Financing Receivable, Modified, Subsequent Default, Number of contracts | Contract | 1,000 | 0
Residential real estate [Member] |  |
Financing Receivable, Modified, Subsequent Default [Line Items] |  |
Financing Receivable, Troubled Debt Restructuring, Subsequent Default | $ | $ 290 | $ 179
Financing Receivable, Modified, Subsequent Default, Number of contracts | Contract | 1,000 | 2,000
Residential real estate [Member] | Senior Lien |  |
Financing Receivable, Modified, Subsequent Default [Line Items] |  |
Financing Receivable, Troubled Debt Restructuring, Subsequent Default | $ | $ 290 | $ 179
Financing Receivable, Modified, Subsequent Default, Number of contracts | Contract | 1,000 | 2,000

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