JUNIOR SUBORDINATED DEBENTURES AND MANDATORILY REDEEMABLE TRUST PREFERRED SECURITIES (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) subsidiary	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jun. 30, 2020 USD ($)
Schedule of Trust Preferred Securities [Line Items]
Number of wholly-owned Grantor Trusts | subsidiary	5
Grantor trusts amount of tier one risk based capital	$ 1,650,872,000	$ 1,528,694,000
Repayment of junior subordinated debentures	0	50,518,000	$ 8,248,000
Loss on extinguishment of debt	$ 0	793,000	$ 2,284,000
Aggregate Liquidation Amount of Trust Preferred Securities [Member]
Schedule of Trust Preferred Securities [Line Items]
Repayment of junior subordinated debentures		$ 50,500,000
Junior Subordinated Debt [Member]
Schedule of Trust Preferred Securities [Line Items]
Long-term Debt, Gross				$ 100,000,000
Debt Instrument, Interest Rate, Stated Percentage	5.00%
Balance outstanding				$ 98,100,000
Subordinated Borrowing, Interest Rate	5.00%
Junior Subordinated Debt [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Schedule of Trust Preferred Securities [Line Items]
Interest Rate Spread	48900.00%
Aggregate Liquidation Amount of Trust Preferred Securities [Member]
Schedule of Trust Preferred Securities [Line Items]
Total TPS liability at par	$ 86,500,000
Aggregate Liquidation Amount of Trust Preferred Securities [Member] | Banner Capital Trust V [Member]
Schedule of Trust Preferred Securities [Line Items]
Total TPS liability at par	25,000,000
Aggregate Liquidation Amount of Trust Preferred Securities [Member] | Banner Capital Trust VI [Member]
Schedule of Trust Preferred Securities [Line Items]
Total TPS liability at par	25,000,000
Aggregate Liquidation Amount of Trust Preferred Securities [Member] | Banner Capital Trust VII [Member]
Schedule of Trust Preferred Securities [Line Items]
Total TPS liability at par	25,000,000
Aggregate Liquidation Amount of Trust Preferred Securities [Member] | Greater Sacramento Bancorp Statutory Trust Two [Member]
Schedule of Trust Preferred Securities [Line Items]
Total TPS liability at par	4,000,000
Aggregate Liquidation Amount of Trust Preferred Securities [Member] | Mission Oaks Statutory Trust One [Member]
Schedule of Trust Preferred Securities [Line Items]
Total TPS liability at par	7,500,000
Aggregate Liquidation Amount of Common Capital Securities [Member]
Schedule of Trust Preferred Securities [Line Items]
Total TPS liability at par	2,678,000
Aggregate Liquidation Amount of Common Capital Securities [Member] | Banner Capital Trust V [Member]
Schedule of Trust Preferred Securities [Line Items]
Total TPS liability at par	774,000
Aggregate Liquidation Amount of Common Capital Securities [Member] | Banner Capital Trust VI [Member]
Schedule of Trust Preferred Securities [Line Items]
Total TPS liability at par	774,000
Aggregate Liquidation Amount of Common Capital Securities [Member] | Banner Capital Trust VII [Member]
Schedule of Trust Preferred Securities [Line Items]
Total TPS liability at par	774,000
Aggregate Liquidation Amount of Common Capital Securities [Member] | Greater Sacramento Bancorp Statutory Trust Two [Member]
Schedule of Trust Preferred Securities [Line Items]
Total TPS liability at par	124,000
Aggregate Liquidation Amount of Common Capital Securities [Member] | Mission Oaks Statutory Trust One [Member]
Schedule of Trust Preferred Securities [Line Items]
Total TPS liability at par	232,000
Debentures Subject to Mandatory Redemption [Member]
Schedule of Trust Preferred Securities [Line Items]
Total TPS liability at par	89,178,000
Fair value adjustment	(22,765,000)
Total TPS liability at fair value	$ 66,413,000
Current Interest Rate	7.19%
Debentures Subject to Mandatory Redemption [Member] | Banner Capital Trusts [Member]
Schedule of Trust Preferred Securities [Line Items]
Grantor trusts amount of tier one risk based capital	$ 86,500,000
Grantor trusts percentage of tier one risk based capital	4.50%
Debentures Subject to Mandatory Redemption [Member] | Banner Capital Trust V [Member]
Schedule of Trust Preferred Securities [Line Items]
Total TPS liability at par	$ 25,774,000
Current Interest Rate	7.21%
Interest Rate Spread, Description	Three-month SOFR
Interest Rate Spread	1.83%
Debentures Subject to Mandatory Redemption [Member] | Banner Capital Trust VI [Member]
Schedule of Trust Preferred Securities [Line Items]
Total TPS liability at par	$ 25,774,000
Current Interest Rate	7.26%
Interest Rate Spread, Description	Three-month SOFR
Interest Rate Spread	1.88%
Debentures Subject to Mandatory Redemption [Member] | Banner Capital Trust VII [Member]
Schedule of Trust Preferred Securities [Line Items]
Total TPS liability at par	$ 25,774,000
Current Interest Rate	7.04%
Interest Rate Spread, Description	Three-month SOFR
Interest Rate Spread	1.64%
Debentures Subject to Mandatory Redemption [Member] | Greater Sacramento Bancorp Statutory Trust Two [Member]
Schedule of Trust Preferred Securities [Line Items]
Total TPS liability at par	$ 4,124,000
Current Interest Rate	7.33%
Interest Rate Spread, Description	Three-month SOFR
Interest Rate Spread	1.94%
Debentures Subject to Mandatory Redemption [Member] | Mission Oaks Statutory Trust One [Member]
Schedule of Trust Preferred Securities [Line Items]
Total TPS liability at par	$ 7,732,000
Current Interest Rate	7.30%
Interest Rate Spread, Description	Three-month SOFR
Interest Rate Spread	1.91%