Subsequent Events	12 Months Ended
Dec. 31, 2025
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On March 10, 2026, First Guaranty and its wholly owned subsidiary, First Guaranty Bank, entered into a definitive purchase and assumption agreement with Armstrong Bank, headquartered in Muskogee, Oklahoma, for the sale of First Guaranty Bank’s Texas operations. The transaction has been approved by the respective boards of directors of the parties and is expected to close during the third quarter of 2026, subject to customary regulatory approvals and other closing conditions. Pursuant to the agreement, First Guaranty Bank will exit the Texas market through the sale of its five Texas branch locations, consisting of four branches in the Dallas–Fort Worth metropolitan area and one branch in Waco, Texas. The transaction is expected to include approximately $270 million in deposits and approximately $110 million in loans. The transaction provides for a deposit premium of 7.65% and is expected to increase First Guaranty Bank’s Tier 1 leverage ratio by approximately 100 basis points upon closing. On March 20, 2026, First Guaranty entered into a second amendment to its promissory note with Smith & Tate Investment, L.L.C., which further amends the promissory note originally dated October 5, 2023, as previously amended on June 4, 2025. The second amendment extends the existing waiver of quarterly principal payments from March 31, 2026 through March 31, 2028 and extends First Guaranty’s option during this period to satisfy interest payments either in cash or through the issuance of shares of the Company’s common stock, based on the closing bid price immediately preceding the interest payment date. Smith & Tate is controlled by Edgar Ray Smith, III, a director and principal shareholder of First Guaranty. On March 20, 2026, First Guaranty entered into a second amendment to its Floating Rate Subordinated Note due March 28, 2034 with Smith & Tate, which further amended the subordinated note previously amended on June 4, 2025. The second amendment extends First Guaranty’s ability to elect to satisfy quarterly interest payments either in cash or through the issuance of shares of First Guaranty’s common stock, based on the closing bid price immediately preceding the interest payment date. Smith & Tate is controlled by Edgar Ray Smith, III, a director and principal shareholder of First Guaranty.

On March 10, 2026, First Guaranty and its wholly owned subsidiary, First Guaranty Bank, entered into a definitive purchase and assumption agreement with Armstrong Bank, headquartered in Muskogee, Oklahoma, for the sale of First Guaranty Bank’s Texas operations. The transaction has been approved by the respective boards of directors of the parties and is expected to close during the third quarter of 2026, subject to customary regulatory approvals and other closing conditions.

Pursuant to the agreement, First Guaranty Bank will exit the Texas market through the sale of its five Texas branch locations, consisting of four branches in the Dallas–Fort Worth metropolitan area and one branch in Waco, Texas. The transaction is expected to include approximately $270 million in deposits and approximately $110 million in loans. The transaction provides for a deposit premium of 7.65% and is expected to increase First Guaranty Bank’s Tier 1 leverage ratio by approximately 100 basis points upon closing.

On March 20, 2026, First Guaranty entered into a second amendment to its promissory note with Smith & Tate Investment, L.L.C., which further amends the promissory note originally dated October 5, 2023, as previously amended on June 4, 2025. The second amendment extends the existing waiver of quarterly principal payments from March 31, 2026 through March 31, 2028 and extends First Guaranty’s option during this period to satisfy interest payments either in cash or through the issuance of shares of the Company’s common stock, based on the closing bid price immediately preceding the interest payment date. Smith & Tate is controlled by Edgar Ray Smith, III, a director and principal shareholder of First Guaranty.

On March 20, 2026, First Guaranty entered into a second amendment to its Floating Rate Subordinated Note due March 28, 2034 with Smith & Tate, which further amended the subordinated note previously amended on June 4, 2025. The second amendment extends First Guaranty’s ability to elect to satisfy quarterly interest payments either in cash or through the issuance of shares of First Guaranty’s common stock, based on the closing bid price immediately preceding the interest payment date. Smith & Tate is controlled by Edgar Ray Smith, III, a director and principal shareholder of First Guaranty.