SECURITIES SOLD UNDER AGREEMENTS TO REPURCHASE - Schedule of Contractual Maturity of the Agreements (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	$ 21,000	$ 36,700
U.S. Government agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	20,983	36,709
Overnight and Continuous \| U.S. Government agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	20,983	36,709
Up to 30 Days \| U.S. Government agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	0	0
30-90 Days \| U.S. Government agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	0	0
Greater than 90 Days \| U.S. Government agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	$ 0	$ 0

SIMMONS FIRST NATIONAL CORP 10-K