v3.25.4

Junior Subordinated Debentures - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 15, 2004
Debt Instrument [Line Items]
Accrued interest payable	$ 1,435,000	$ 962,000
Junior Subordinated Debentures
Debt Instrument [Line Items]
Total liability, at par	$ 3,609,000	$ 3,609,000		$ 3,600,000
Effective interest rate	6.08%	6.72%
Interest expenses	$ 243,000	$ 279,000	$ 271,000
Accrued interest payable	10,000	$ 11,000
Principal payments due in next five years	$ 0
Junior Subordinated Debentures \| London Interbank Offered Rate (LIBOR) 1
Debt Instrument [Line Items]
Debt instrument, variable rate	2.10%
Junior Subordinated Debentures \| SOFR
Debt Instrument [Line Items]
Debt instrument, variable rate	0.26%
Junior Subordinated Debentures \| SOFR \| Maximum
Debt Instrument [Line Items]
Debt instrument, variable rate	2.10%

Debt instrument principal payment due in next five years.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Interest expense incurred during the reporting period on junior subordinated debentures. Includes amortization of expenses incurred in the issuance of subordinated notes and debentures.

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COASTAL FINANCIAL CORP 10-K