COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Reserve for Unfunded Loan Commitments	$ 12,400	$ 13,300
Mortgage loan applications, day Interest rate is locked	45 days
Minimum [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Mortgage loan applications, day Interest rate is locked	30 days
Maximum [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Mortgage loan applications, day Interest rate is locked	60 days
Limited Partner [Member]
Schedule of Fair Value, Off-Balance Sheet Risks, Limited Partnerships, Commitment [Line Items]
Fair Value Disclosure, Off Balance Sheet Risk, Amount Funded, Commitment	$ 7,642	2,819
Fair Value Disclosure, Off Balance Sheet Risk, Unfunded Amount, Commitment	9,858	7,181
Commitments to extend credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract or Notional Amount	3,527,143	3,207,072
Standby letters of credit and financial guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract or Notional Amount	21,830	18,415
Commitments to originate loans
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract or Notional Amount	106,609	101,426
Risk Participation Agreement [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract or Notional Amount	40,064	40,949
Commitments to originate loans held for sale
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract or Notional Amount	106,590	169,653
Commitments to sell loans secured by one- to four-family residential properties
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract or Notional Amount	27,006	79,414
Loss on Contract Termination for Default	0
Commitments to sell securities related to mortgage banking activities
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract or Notional Amount	$ 127,580	$ 204,000

Fair Value Disclosure, Off Balance Sheet Risk, Amount Funded, Commitment

No definition available.

Name:	banr_FairValueDisclosureOffBalanceSheetRiskAmountFundedCommitment
Namespace Prefix:	banr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair Value Disclosure, Off Balance Sheet Risk, Unfunded Amount, Commitment

+ References

No definition available.

+ Details

Name:	banr_FairValueDisclosureOffBalanceSheetRiskUnfundedAmountCommitment
Namespace Prefix:	banr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Mortgage Loan Applications, Day Interest Rate is Locked

+ References

No definition available.

+ Details

Name:	banr_MortgageLoanApplicationsDayInterestRateIsLocked
Namespace Prefix:	banr_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Unfunded Loan Commitments

+ References

No definition available.

+ Details

Name:	banr_ReserveforUnfundedLoanCommitments
Namespace Prefix:	banr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Schedule of Fair Value, Off-Balance Sheet Risks, Limited Partnerships, Commitment [Line Items]

+ References

No definition available.

+ Details

Name:	banr_ScheduleOfFairValueOffBalanceSheetRisksLimitedPartnershipsCommitmentLineItems
Namespace Prefix:	banr_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The face amount of financial liabilities, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition.

+ References

No definition available.

+ Details

Name:	us-gaap_FairValueDisclosureOffbalanceSheetRisksFaceAmountLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_FairValueOffBalanceSheetRisksDisclosureInformationLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of the loss on termination of a contract for default.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 912
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=123358902&loc=d3e52595-109384

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 912
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6471639&loc=d3e52679-109385

+ Details

Name:	us-gaap_LossOnContractTerminationForDefault
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_LimitedPartnerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CommitmentsToExtendCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_FinancialStandbyLetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_LoanOriginationCommitmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=banr_RiskParticipationAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=banr_LoansHeldForSaleOriginationCommitmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=banr_CommitmentstoSellLoansSecuredbyonetofourResidentialPropertiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=banr_CommitmentsToSellMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: