v3.25.4

ACQUISITIONS - Narrative (Details)			12 Months Ended
ACQUISITIONS - Narrative (Details)	Apr. 08, 2022 USD ($) shares	Nov. 20, 2021 USD ($)	Dec. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2021 USD ($) branch
Business Combination [Line Items]
Acquisition-related costs			$ 0	$ 0	$ 1,400,000
Spirit of Texas Bancshares, Inc.
Business Combination [Line Items]
Shares issued (in shares) \| shares	18,275,074
Stock issued for acquisition	$ 464,900,000
Payments to acquire businesses, gross	1,393,508.9
Number of bank branches acquired \| branch						35
Assets acquired, after acquisition method adjustments						$ 3,110,000,000
Loans acquired, after acquisition method adjustments						2,290,000,000
Customer deposits acquired, after acquisition method adjustments						$ 2,720,000,000
Goodwill	$ 174,100,000	$ 174,146,000

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SIMMONS FIRST NATIONAL CORP 10-K