OTHER BORROWINGS (Textuals) (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Funds Borrowed Against Current Borrowing Capacity	$ 182,877,000	$ 232,799,000
Debt Securities Pledged as Collateral for Repurchase Transaction Accounts, Amortized Costs	266,600,000
Repurchase Agreements [Member] \| Retail repurchase agreements [Member]
Debt Instrument [Line Items]
Funds Borrowed Against Current Borrowing Capacity	$ 182,877,000	232,799,000
Repurchase Agreements [Member] \| Retail repurchase agreements [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Repurchase agreements, interest rate	0.05%
Repurchase Agreements [Member] \| Retail repurchase agreements [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Repurchase agreements, interest rate	4.64%
Federal Reserve Bank Advances [Member] \| Federal Reserve Bank of San Francisco [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 1,440,000,000
Funds Borrowed Against Current Borrowing Capacity	0	0
Subsidiary, Banner Bank [Member] \| Repurchase Agreements [Member]
Debt Instrument [Line Items]
Line of credit, current	0
Subsidiary, Banner Bank [Member] \| Federal Funds Purchased [Member]
Debt Instrument [Line Items]
Line of credit, current	$ 0	$ 0

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Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

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