ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narratives (Details)	12 Months Ended
	Dec. 31, 2024 USD ($) building	Dec. 31, 2023 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Impairment of correspondent bank stock	$ 0	$ 0
Loans, net	2,407,235,000	2,506,984,000
Term deposits	2,514,209,000	2,529,039,000
Performance based incentive fees	0	0
Reciprocal Deposits
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Term deposits	963,200,000
Deposit Brokers
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Term deposits	134,500,000
MSLP loan | COVID-19
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans, net	1,700,000	5,100,000
Cash, Securities, and Other | PPP Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans, net	2,000,000	4,200,000
Consumer and Other | PPP Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans, net	$ 7,500,000	$ 14,100,000
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Remaining amortization period (in years)	1 year
Minimum | Leasehold improvements, including artwork
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life (in years)	7 years
Minimum | Software
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life (in years)	3 years
Minimum | Furniture/equipment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life (in years)	3 years
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Remaining amortization period (in years)	10 years
Maximum | Leasehold improvements, including artwork
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life (in years)	15 years
Maximum | Software
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life (in years)	7 years
Maximum | Furniture/equipment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life (in years)	7 years
Teton Financial Services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of buildings acquired | building	3
Teton Financial Services | Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life (in years)	25 years
Teton Financial Services | Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life (in years)	50 years
Deposits Benchmark | Customer Concentration Risk | Reciprocal Deposits
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Concentration risk (as a percent)	38.30%
Deposits Benchmark | Customer Concentration Risk | Deposit Brokers
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Concentration risk (as a percent)	5.40%
Deposits Benchmark | Customer Concentration Risk | 10 Largest Depositors
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Concentration risk (as a percent)	32.00%
Real Estate | Loans Receivable | Collateral concentration risk
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Concentration risk (as a percent)	78.90%	76.10%