ACCOUNTING STANDARDS RECENTLY ISSUED OR ADOPTED	3 Months Ended
Mar. 31, 2016
Accounting Changes and Error Corrections [Abstract]
ACCOUNTING STANDARDS RECENTLY ISSUED OR ADOPTED	ACCOUNTING STANDARDS RECENTLY ISSUED OR ADOPTED Revenue from Contracts with Customers In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers, which creates Topic 606 and supersedes Topic 605, Revenue Recognition. The core principle of Topic 606 is that an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In general, the new guidance requires companies to use more judgment and make more estimates than under current guidance, including identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation. Under the terms of ASU 2015-14 the standard is effective for interim and annual periods beginning after December 15, 2017. Early application is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. For financial reporting purposes, the standard allows for either full retrospective adoption, meaning the standard is applied to all of the periods presented, or modified retrospective adoption, meaning the standard is applied only to the most current period presented in the financial statements with the cumulative effect of initially applying the standard recognized at the date of initial application. The Company is currently evaluating the provisions of ASU No. 2014-09 to determine the potential impact the standard will have on the Company’s Consolidated Financial Statements. In April 2016, FASB issued ASU No. 2016-10, Identifying Performance Obligations and Licensing. The amendments in this ASU do not change the core principle of the guidance in Topic 606. Rather, the amendments in this ASU clarify the following two aspects of Topic 606: identifying performance obligations and the licensing implementation guidance, while retaining the related principles for those areas. The amendments in this ASU affect the guidance in ASU 2014-09, discussed above, which is not yet effective. The effective date and transition requirements for the amendments in this ASU are the same as the effective date and transition requirements in Topic 606 (Revenues from Contracts with Customers). The Company is evaluating the provisions of this ASU in conjunction with ASU No. 2014-09 to determine the potential impact Topic 606 and its amendments will have on the Company’s Consolidated Financial Statements. Customer's Accounting for Fees Paid in a Cloud Computing Arrangement In April 2015, FASB issued ASU No. 2015-05, Customer's Accounting for Fees Paid in a Cloud Computing Arrangement. The amendments in this ASU provide guidance to customers in cloud computing arrangements about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. The amendments were effective for adoption of annual periods, including interim periods within those annual periods, beginning after December 15, 2015 and were adopted by the Company, as of January 1, 2016. This ASU did not have a material effect on the Company's Consolidated Financial Statements. Business Combinations—Simplifying the Accounting for Measurement-Period Adjustments In September 2015, FASB issued ASU No. 2015-16, Simplifying the Accounting for Measurement-Period Adjustments. The amendments in this ASU require that an acquirer recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period when the adjustment amounts are determined. The acquirer is required to record in the same period's financial statements the effect on earnings from changes in depreciation, amortization, or other income effects resulting from the change to provisional amounts, calculated as if the accounting had been completed at the acquisition date. The acquirer must present separately on the income statement, or disclose in the notes, the amount recorded in current-period earnings that would have been recorded in previous reporting periods if the provisional amount had been recognized at the acquisition date. The amendments in this ASU were effective for fiscal years beginning after December 15, 2015 and were adopted by the Company, as of January 1, 2016. As a result of this ASU, the adjustments recorded during the three months ended March 31, 2016 to the provisional amounts recorded as of December 31, 2015 related to the acquisition of Starbuck Bancshares, Inc. (Starbuck) were recorded in the current period. Recognition and Measurement of Financial Assets and Financial Liabilities In January 2016, FASB issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities. The amendments in this ASU require equity securities to be measured at fair value with changes in the fair value recognized through net income. The amendments allow equity investments that do not have readily determinable fair values to be remeasured at fair value under certain circumstances and require enhanced disclosures about those investments. This ASU simplifies the impairment assessment of equity investments without readily determinable fair values. This ASU also eliminate the requirement to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet. The amendments in this ASU require separate presentation in other comprehensive income of the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. This ASU excludes from net income gains or losses that the entity may not realize because those financial liabilities are not usually transferred or settled at their fair values before maturity. The amendments in this ASU require separate presentation of financial assets and financial liabilities by measurement category and form of financial asset (that is, securities or loans and receivables) on the balance sheet or in the accompanying notes to the financial statements. The amendments in this ASU are effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The Company is currently evaluating the provisions of ASU No. 2016-01 to determine the potential impact the new standard will have on the Company's Consolidated Financial Statements. Leases (Topic 842) In February 2016, FASB issued ASU No. 2016-02, Leases (Topic 842). The amendments in this ASU require lessees to recognize the following for all leases (with the exception of short-term) at the commencement date; a lease liability, which is a lessee‘s obligation to make lease payments arising from a lease, measured on a discounted basis; and a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. The amendments in this ASU leave lessor accounting largely unchanged, although certain targeted improvements were made to align lessor accounting with the lessee accounting model. This ASU simplifies the accounting for sale and leaseback transactions primarily because lessees must recognize lease assets and lease liabilities. Lessees will no longer be provided with a source of off-balance sheet financing. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early application is permitted upon issuance. Lessees (for capital and operating leases) and lessors (for sales-type, direct financing, and operating leases) must apply a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The modified retrospective approach would not require any transition accounting for leases that expired before the earliest comparative period presented. Lessees and lessors may not apply a full retrospective transition approach. The Company is currently evaluating the provisions of ASU No. 2016-02 to determine the potential impact the new standard will have on the Company's Consolidated Financial Statements. Derivatives and Hedging (Topic 815) In March 2016, FASB issued ASU No. 2016-05, Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships. The amendments in this ASU clarify that a change in the counterparty to a derivative instrument that has been designated as the hedging instrument under Topic 815 (Derivatives and Hedging) does not, in and of itself, require dedesignation of that hedging relationship provided that all other hedge accounting criteria continue to be met. The amendments in this ASU are effective for financial statements issued for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. An entity has an option to apply the amendments in this ASU on either a prospective basis or a modified retrospective basis. Early adoption is permitted, including adoption in an interim period. At March 31, 2016, Banner had four swap relationships using hedge accounting with a total market value of approximately $1.0 million. This ASU is not expected to have a material impact on the Company’s Consolidated Financial Statements. In March 2016, FASB issued ASU No. 2016-06, Contingent Put and Call Options in Debt Instruments. The amendments in this ASU clarify the requirements for assessing whether contingent call (put) options that can accelerate the payment of principal on debt instruments are clearly and closely related to their debt hosts. To determine how to account for debt instruments with embedded features, including contingent put and call options, an entity is required to assess whether the embedded derivatives must be bifurcated from the host contract and accounted for separately. Part of this assessment consists of evaluating whether the embedded derivative features are clearly and closely related to the debt host. Under existing guidance, for contingently exercisable options to be considered clearly and closely related to a debt host, they must be indexed only to interest rates or credit risk. ASU 2016-06 addresses inconsistent interpretations of whether an event that triggers an entity’s ability to exercise the embedded contingent option must be indexed to interest rates or credit risk for that option to qualify as clearly and closely related. Diversity in practice has developed because the existing four-step decision sequence in ASC 815 focuses only on whether the payoff was indexed to something other than an interest rate or credit risk. As a result, entities have been uncertain whether they should (1) determine whether the embedded features are clearly and closely related to the debt host solely on the basis of the four-step decision sequence or (2) first apply the four-step decision sequence and then also evaluate whether the event triggering the exercisability of the contingent put or call option is indexed only to an interest rate or credit risk. This ASU clarifies that in assessing whether an embedded contingent put or call option is clearly and closely related to the debt host, an entity is required to perform only the four-step decision sequence in ASC 815 as amended by this ASU. The entity does not have to separately assess whether the event that triggers its ability to exercise the contingent option is itself indexed only to interest rates or credit risk. The amendments in this ASU are effective for financial statements issued for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. This ASU is not expected to have a material impact on the Company’s Consolidated Financial Statements. Compensation-Stock Compensation (Topic 718) In March 2016, FASB issued ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting. FASB is issuing this ASU as part of its Simplification Initiative. The areas for simplification in this ASU involve several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The amendments in this ASU are effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods. Early adoption is permitted for any entity in any interim or annual period. If an entity early adopts the amendments in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes that interim period. An entity that elects early adoption must adopt all of the amendments in the same period. Amendments in this ASU related to the timing of when excess tax benefits are recognized, minimum statutory withholding requirements, forfeitures, and intrinsic value should be applied using a modified retrospective transition method by means of a cumulative-effect adjustment to equity as of the beginning of the period in which the guidance is adopted. Amendments related to the presentation of employee taxes paid on the statement of cash flows when an employer withholds shares to meet the minimum statutory withholding requirement should be applied retrospectively. Amendments in this ASU require recognition of excess tax benefits and tax deficiencies in the income statement and the practical expedient for estimating expected term should be applied prospectively. An entity may elect to apply the amendments in this ASU related to the presentation of excess tax benefits on the statement of cash flows using either a prospective transition method or a retrospective transition method. This ASU is not expected to have a material impact on the Company’s Consolidated Financial Statements.

ACCOUNTING STANDARDS RECENTLY ISSUED OR ADOPTED

Revenue from Contracts with Customers

In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers, which creates Topic 606 and supersedes Topic 605, Revenue Recognition. The core principle of Topic 606 is that an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In general, the new guidance requires companies to use more judgment and make more estimates than under current guidance, including identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation. Under the terms of ASU 2015-14 the standard is effective for interim and annual periods beginning after December 15, 2017. Early application is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. For financial reporting purposes, the standard allows for either full retrospective adoption, meaning the standard is applied to all of the periods presented, or modified retrospective adoption, meaning the standard is applied only to the most current period presented in the financial statements with the cumulative effect of initially applying the standard recognized at the date of initial application. The Company is currently evaluating the provisions of ASU No. 2014-09 to determine the potential impact the standard will have on the Company’s Consolidated Financial Statements.

In April 2016, FASB issued ASU No. 2016-10, Identifying Performance Obligations and Licensing. The amendments in this ASU do not change the core principle of the guidance in Topic 606. Rather, the amendments in this ASU clarify the following two aspects of Topic 606: identifying performance obligations and the licensing implementation guidance, while retaining the related principles for those areas. The amendments in this ASU affect the guidance in ASU 2014-09, discussed above, which is not yet effective. The effective date and transition requirements for the amendments in this ASU are the same as the effective date and transition requirements in Topic 606 (Revenues from Contracts with Customers). The Company is evaluating the provisions of this ASU in conjunction with ASU No. 2014-09 to determine the potential impact Topic 606 and its amendments will have on the Company’s Consolidated Financial Statements.

Customer's Accounting for Fees Paid in a Cloud Computing Arrangement

In April 2015, FASB issued ASU No. 2015-05, Customer's Accounting for Fees Paid in a Cloud Computing Arrangement. The amendments in this ASU provide guidance to customers in cloud computing arrangements about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. The amendments were effective for adoption of annual periods, including interim periods within those annual periods, beginning after December 15, 2015 and were adopted by the Company, as of January 1, 2016. This ASU did not have a material effect on the Company's Consolidated Financial Statements.

Business Combinations—Simplifying the Accounting for Measurement-Period Adjustments

In September 2015, FASB issued ASU No. 2015-16, Simplifying the Accounting for Measurement-Period Adjustments. The amendments in this ASU require that an acquirer recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period when the adjustment amounts are determined. The acquirer is required to record in the same period's financial statements the effect on earnings from changes in depreciation, amortization, or other income effects resulting from the change to provisional amounts, calculated as if the accounting had been completed at the acquisition date. The acquirer must present separately on the income statement, or disclose in the notes, the amount recorded in current-period earnings that would have been recorded in previous reporting periods if the provisional amount had been recognized at the acquisition date. The amendments in this ASU were effective for fiscal years beginning after December 15, 2015 and were adopted by the Company, as of January 1, 2016. As a result of this ASU, the adjustments recorded during the three months ended March 31, 2016 to the provisional amounts recorded as of December 31, 2015 related to the acquisition of Starbuck Bancshares, Inc. (Starbuck) were recorded in the current period.

Recognition and Measurement of Financial Assets and Financial Liabilities

In January 2016, FASB issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities. The amendments in this ASU require equity securities to be measured at fair value with changes in the fair value recognized through net income. The amendments allow equity investments that do not have readily determinable fair values to be remeasured at fair value under certain circumstances and require enhanced disclosures about those investments. This ASU simplifies the impairment assessment of equity investments without readily determinable fair values. This ASU also eliminate the requirement to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet. The amendments in this ASU require separate presentation in other comprehensive income of the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. This ASU excludes from net income gains or losses that the entity may not realize because those financial liabilities are not usually transferred or settled at their fair values before maturity. The amendments in this ASU require separate presentation of financial assets and financial liabilities by measurement category and form of financial asset (that is, securities or loans and receivables) on the balance sheet or in the accompanying notes to the financial statements. The amendments in this ASU are effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The Company is currently evaluating the provisions of ASU No. 2016-01 to determine the potential impact the new standard will have on the Company's Consolidated Financial Statements.

Leases (Topic 842)

In February 2016, FASB issued ASU No. 2016-02, Leases (Topic 842). The amendments in this ASU require lessees to recognize the following for all leases (with the exception of short-term) at the commencement date; a lease liability, which is a lessee‘s obligation to make lease payments arising from a lease, measured on a discounted basis; and a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. The amendments in this ASU leave lessor accounting largely unchanged, although certain targeted improvements were made to align lessor accounting with the lessee accounting model. This ASU simplifies the accounting for sale and leaseback transactions primarily because lessees must recognize lease assets and lease liabilities. Lessees will no longer be provided with a source of off-balance sheet financing. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early application is permitted upon issuance. Lessees (for capital and operating leases) and lessors (for sales-type, direct financing, and operating leases) must apply a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The modified retrospective approach would not require any transition accounting for leases that expired before the earliest comparative period presented. Lessees and lessors may not apply a full retrospective transition approach. The Company is currently evaluating the provisions of ASU No. 2016-02 to determine the potential impact the new standard will have on the Company's Consolidated Financial Statements.

Derivatives and Hedging (Topic 815)

In March 2016, FASB issued ASU No. 2016-05, Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships. The amendments in this ASU clarify that a change in the counterparty to a derivative instrument that has been designated as the hedging instrument under Topic 815 (Derivatives and Hedging) does not, in and of itself, require dedesignation of that hedging relationship provided that all other hedge accounting criteria continue to be met. The amendments in this ASU are effective for financial statements issued for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. An entity has an option to apply the amendments in this ASU on either a prospective basis or a modified retrospective basis. Early adoption is permitted, including adoption in an interim period. At March 31, 2016, Banner had four swap relationships using hedge accounting with a total market value of approximately $1.0 million. This ASU is not expected to have a material impact on the Company’s Consolidated Financial Statements.

In March 2016, FASB issued ASU No. 2016-06, Contingent Put and Call Options in Debt Instruments. The amendments in this ASU clarify the requirements for assessing whether contingent call (put) options that can accelerate the payment of principal on debt instruments are clearly and closely related to their debt hosts. To determine how to account for debt instruments with embedded features, including contingent put and call options, an entity is required to assess whether the embedded derivatives must be bifurcated from the host contract and accounted for separately. Part of this assessment consists of evaluating whether the embedded derivative features are clearly and closely related to the debt host. Under existing guidance, for contingently exercisable options to be considered clearly and closely related to a debt host, they must be indexed only to interest rates or credit risk. ASU 2016-06 addresses inconsistent interpretations of whether an event that triggers an entity’s ability to exercise the embedded contingent option must be indexed to interest rates or credit risk for that option to qualify as clearly and closely related. Diversity in practice has developed because the existing four-step decision sequence in ASC 815 focuses only on whether the payoff was indexed to something other than an interest rate or credit risk. As a result, entities have been uncertain whether they should (1) determine whether the embedded features are clearly and closely related to the debt host solely on the basis of the four-step decision sequence or (2) first apply the four-step decision sequence and then also evaluate whether the event triggering the exercisability of the contingent put or call option is indexed only to an interest rate or credit risk. This ASU clarifies that in assessing whether an embedded contingent put or call option is clearly and closely related to the debt host, an entity is required to perform only the four-step decision sequence in ASC 815 as amended by this ASU. The entity does not have to separately assess whether the event that triggers its ability to exercise the contingent option is itself indexed only to interest rates or credit risk. The amendments in this ASU are effective for financial statements issued for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. This ASU is not expected to have a material impact on the Company’s Consolidated Financial Statements.

Compensation-Stock Compensation (Topic 718)

In March 2016, FASB issued ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting. FASB is issuing this ASU as part of its Simplification Initiative. The areas for simplification in this ASU involve several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The amendments in this ASU are effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods. Early adoption is permitted for any entity in any interim or annual period. If an entity early adopts the amendments in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes that interim period. An entity that elects early adoption must adopt all of the amendments in the same period. Amendments in this ASU related to the timing of when excess tax benefits are recognized, minimum statutory withholding requirements, forfeitures, and intrinsic value should be applied using a modified retrospective transition method by means of a cumulative-effect adjustment to equity as of the beginning of the period in which the guidance is adopted. Amendments related to the presentation of employee taxes paid on the statement of cash flows when an employer withholds shares to meet the minimum statutory withholding requirement should be applied retrospectively. Amendments in this ASU require recognition of excess tax benefits and tax deficiencies in the income statement and the practical expedient for estimating expected term should be applied prospectively. An entity may elect to apply the amendments in this ASU related to the presentation of excess tax benefits on the statement of cash flows using either a prospective transition method or a retrospective transition method. This ASU is not expected to have a material impact on the Company’s Consolidated Financial Statements.