LOANS AND THE ALLOWANCE FOR CREDIT LOSSES - Narrative (Details) $ in Thousands	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2026 USD ($) loan	Mar. 31, 2026 USD ($)	Jun. 30, 2025 loan	Jun. 30, 2026 USD ($) loan	Jun. 30, 2025 loan	Dec. 31, 2025 USD ($) loan
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans (includes $1,758 and $3,182 measured at fair value, respectively)	$ 2,713,688			$ 2,713,688		$ 2,649,484
Number of loans modified | loan	0		0		0
Number of loans experiencing default | loan	1		0	1	0
Financing receivable, subsequent default	$ 700			$ 700
Number of OREO loans sold | loan						2
Gains (Losses) on Sales of Other Real Estate		$ 0				$ 500
Other real estate owned, net	$ 0			$ 0		$ 3,040
Financing Receivable, Number of Loans Secured by Real Estate in Foreclosure Process | loan	0			0		0
Accrued interest receivable	$ 10,400			$ 10,400		$ 10,400
Significant Unobservable Inputs (Level 3)
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss on non-performing loans	2,400			2,400		3,300
Consumer and other
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans (includes $1,758 and $3,182 measured at fair value, respectively)	21,092			21,092		22,778
Cash, securities, and other
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans (includes $1,758 and $3,182 measured at fair value, respectively)	181,949			181,949		164,726
Commercial and industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans (includes $1,758 and $3,182 measured at fair value, respectively)	234,237			234,237		225,281
Owner occupied CRE
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans (includes $1,758 and $3,182 measured at fair value, respectively)	221,515			221,515		204,078
Simmons Bank
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans (includes $1,758 and $3,182 measured at fair value, respectively)	$ 113,800			$ 113,800		$ 121,300