Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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Percentage increase in the stated interest rate on a short-term debt instrument.

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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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No definition available.

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The portion of the carrying amount of short-term borrowings outstanding as of the balance sheet date which accrues interest at a set, unchanging rate.

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No definition available.

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The portion of the carrying amount of short-term borrowings outstanding as of the balance sheet date, which accrues interest at a rate subject to change from time to time.

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No definition available.

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Weighted average interest rate of short-term debt outstanding calculated at point in time.

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Weighted average interest rate of short-term debt outstanding calculated over time.

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No definition available.

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- Definition

For the form of debt having an initial term of less than one year or less than the normal operating cycle, if longer, average borrowings during the period.

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For the form of debt having an initial term of less than one year or less than the normal operating cycle, if longer, the maximum amount borrowed at any time during the period.

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No definition available.

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For the form of debt having an initial term of less than one year or less than the normal operating cycle, if longer, maximum month-end borrowings during the period.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of subordinated debt (with initial maturities beyond one year or beyond the operating cycle if longer). Subordinated debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.

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The portion of the carrying value of subordinated debt as of the balance sheet date that is scheduled to be repaid within one year or in the normal operating cycle, if longer. Subordinated debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.

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Carrying value as of the balance sheet date of collateralized/uncollateralized debt obligation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Subordinated debt places a lender in a lien position behind the primary lender of the company.

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Short-Term and Other Borrowings - Summary of Federal Funds Purchased, Securities Sold Under Agreements to Repurchase and Other Short-term Borrowings (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Short-term Debt [Line Items]
Long-Term Subordinated Debentures, net of unamortized debt issuance costs	$ 73,864		$ 73,864		$ 73,740
Total Subordinated Debentures	104,213		104,213		104,089
First Citizens Statutory Trust II [Member]
Short-term Debt [Line Items]
Subordinated Debentures	7,732		7,732		7,732
First Citizens Statutory Trust III [Member]
Short-term Debt [Line Items]
Subordinated Debentures	12,887		12,887		12,887
First Citizens Statutory Trust IV [Member]
Short-term Debt [Line Items]
Subordinated Debentures	5,155		5,155		5,155
Futura TPF Trust I [Member]
Short-term Debt [Line Items]
Subordinated Debentures	2,578		2,578		2,578
Futura TPF Trust II [Member]
Short-term Debt [Line Items]
Subordinated Debentures	1,997		1,997		1,997
Federal Funds Purchased [Member]
Short-term Debt [Line Items]
Short-term borrowings	0		0		0
Short Term Borrowings, FHLB advances [Member]
Short-term Debt [Line Items]
Short-term borrowings	232,000		232,000		339,000
Maximum indebtedness	$ 412,200	$ 497,500	$ 465,000	$ 501,500
Maximum indebtedness, Rate	4.44%	5.50%	4.44%	5.50%
End of period balance	$ 232,000	$ 287,047	$ 232,000	$ 287,047
End of period balance, Rate	4.20%	4.88%	4.20%	4.88%
Average balance	$ 272,985	$ 388,022	$ 346,737	$ 385,801
Average rate paid	4.45%	5.46%	4.47%	5.51%
Short Term Borrowings, FHLB advances [Member] \| Single Maturity Fixed Rate Advances [Member]
Short-term Debt [Line Items]
Short-term borrowings	$ 100,000		$ 100,000		$ 0
Interest rate on balance	4.22%		4.22%		0.00%
Short Term Borrowings, FHLB advances [Member] \| Overnight [Member]
Short-term Debt [Line Items]
Short-term borrowings	$ 132,000		$ 132,000		$ 339,000
Interest rate on balance	4.18%		4.18%		4.42%