Mortgage Loan Applications, Day Interest Rate is Locked

No definition available.

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

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482907/825-10-50-11

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 825
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478898/942-825-50-1

+ 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

+ 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
-Topic 912
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482291/912-20-45-5

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 912
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482269/912-20-50-1

+ 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_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=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:

COMMITMENTS AND CONTINGENCIES (Commitments Without Recorded Liability) (Details) - USD ($)	3 Months Ended	6 Months Ended
	Jun. 30, 2026	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2025
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Reserve for Unfunded Loan Commitments	$ 15,100,000	$ 15,100,000		$ 15,000,000.0
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
Commitments to Extend Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract or Notional Amount	4,241,995,000	$ 4,241,995,000		3,978,474,000
Financial Standby Letter of Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract or Notional Amount	29,028,000	29,028,000		26,406,000
Risk Participation Agreement [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract or Notional Amount	40,098,000	40,098,000		41,191,000
Loans Held for Sale Origination Commitments [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract or Notional Amount	46,140,000	46,140,000		39,895,000
Commitments to Sell Loans Secured by one to four Residential Properties [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract or Notional Amount	29,495,000	29,495,000		43,264,000
Counterparty default losses on forward contracts	0		$ 0
Commitments to Sell Mortgage Backed Securities [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract or Notional Amount	$ 34,500,000	$ 34,500,000		$ 27,250,000