INTEREST-BEARING DEPOSITS AND SECURITIES (Securities Pledged) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012
Pledged Financial Instruments, Not Separately Reported, Securities [Abstract]
State and local governments public deposits, amortized cost	$ 92,740
Interest rate swap counterparties, amortized cost	10,841
Retail repurchase transaction accounts, amortized cost	101,315
Other, amortized cost	5,976
Total pledged securities, amortized cost	210,872
State and local governments public deposits, fair value	99,358
Interest rate swap counterparties, fair value	11,025
Retail repurchase transaction accounts, fair value	104,036
Other, fair value	6,149
Total pledged securities, fair value	$ 220,568

Pledged Financial Instruments, Not Separately Reported, Securities, Fair Value

No definition available.

Name:	banr_PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesFairValue
Namespace Prefix:	banr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Pledged Financial Instruments, Not Separately Reported, Securities for Interest Rate Swap Counterparties

+ References

No definition available.

+ Details

Name:	banr_PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesForInterestRateSwapCounterparties
Namespace Prefix:	banr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Pledged Financial Instruments, Not Separately Reported, Securities for Interest Rate Swap Counterparties, Fair Value

+ References

No definition available.

+ Details

Name:	banr_PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesForInterestRateSwapCounterpartiesFairValue
Namespace Prefix:	banr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Pledged Financial Instruments, Not Separately Reported, Securities for Other Debt Facilities, Fair Value

+ References

No definition available.

+ Details

Name:	banr_PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesForOtherDebtFacilitiesFairValue
Namespace Prefix:	banr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Pledged Financial Instruments, Not Separately Reported, Securities for Repurchase Agreements, Fair Value

+ References

No definition available.

+ Details

Name:	banr_PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesForRepurchaseAgreementsFairValue
Namespace Prefix:	banr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Pledged Financial Instruments, Not Separately Reported, State and Local Government Public Deposits

+ References

No definition available.

+ Details

Name:	banr_PledgedFinancialInstrumentsNotSeparatelyReportedStateAndLocalGovernmentPublicDeposits
Namespace Prefix:	banr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Pledged Financial Instruments, Not Separately Reported, State and Local Government Public Deposits, Fair Value

+ References

No definition available.

+ Details

Name:	banr_PledgedFinancialInstrumentsNotSeparatelyReportedStateAndLocalGovernmentPublicDepositsFairValue
Namespace Prefix:	banr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

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

- Definition

The carrying amount as of the date of the latest financial statement presented of securities which are owned but transferred to serve as collateral for debt facilities other than FHLB loans, repurchase agreements and letter of credit arrangements, and for which the transferee does not have the right by contract or custom to sell or re-pledge them to an unrelated party.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 30

-Section 50

-Paragraph 1A

-Subparagraph (b)(1)(i)

-URI http://asc.fasb.org/extlink&oid=7523297&loc=SL6224234-111729

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS140-4/FIN46(R)-8

-Paragraph B6

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 140

-Paragraph 17

-Subparagraph a(2)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesForOtherDebtFacilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The carrying amount as of the date of the latest financial statement presented of securities which are owned but transferred to serve as collateral for repurchase agreements, and for which the transferee does not have the right by contract or custom to sell or re-pledge them to an unrelated party.

+ References

+ Details

Name:	us-gaap_PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesForRepurchaseAgreements
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Sum of the carrying amounts as of the date of the latest financial statement presented of securities which are owned but transferred to another party to serve as collateral to partially or fully secure a debt obligation, repurchase agreement or other current or potential obligation, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

+ References

+ Details

Name:	us-gaap_PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesPledged
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant