ACQUISITIONS - Narrative (Details)		3 Months Ended	12 Months Ended
	May 15, 2020 USD ($)	Sep. 30, 2020 item Office	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Feb. 10, 2020 item	Dec. 31, 2019 USD ($)
Business Acquisition [Line Items]
Goodwill	$ 4,500,000		$ 30,588,000	$ 24,191,000		$ 19,686,000
Goodwill acquired during the period			6,397,000	4,505,000
Simmons Bank
Business Acquisition [Line Items]
Number of branches acquired | item					3
Number of branches closed | item		2
Loan production offices acquired | item					1
Loan production offices closed | Office		1
Purchase consideration	$ 61,599,000
Deposit premium	6.06%
Goodwill	$ 4,505,000
Loans, net	119,552,000
Contractual balance	120,600,000
Discount on loans	$ 1,100,000
Discount on loans (in percent)	0.90%
Allowance for Loan and Lease Losses, Loans Acquired	$ 0
Acquisition cost				$ 700,000
Teton Financial Services
Business Acquisition [Line Items]
Purchase consideration			51,319,000
Goodwill			6,397,000
Loans, net			252,275,000
Contractual balance			256,300,000
Discount on loans			$ 4,000,000.0
Discount on loans (in percent)			1.60%
Acquisition cost			$ 4,100,000