BASIS OF PRESENTATION AND CRITICAL ACCOUNTING POLICIES	3 Months Ended
Mar. 31, 2013
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BASIS OF PRESENTATION AND CRITICAL ACCOUNTING POLICIES	BASIS OF PRESENTATION AND CRITICAL ACCOUNTING POLICIES The accompanying unaudited consolidated financial statements include the accounts of Banner Corporation (the Company or Banner), a bank holding company incorporated in the State of Washington and its wholly-owned subsidiaries, Banner Bank and Islanders Bank (the Banks). These unaudited consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (GAAP) for interim financial information and in accordance with the instructions to Form 10-Q and Article 10 of Regulation S-X as promulgated by the Securities and Exchange Commission (SEC). In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation of the financial position and results of operations for the periods presented have been included. Certain information and disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to the rules and regulations of the SEC. Certain reclassifications have been made to the 2012 Consolidated Financial Statements and/or schedules to conform to the 2013 presentation. These reclassifications may have affected certain ratios for the prior periods. The effect of these reclassifications is considered immaterial. All significant intercompany transactions and balances have been eliminated. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect amounts reported in the financial statements. Various elements of the Company’s accounting policies, by their nature, are inherently subject to estimation techniques, valuation assumptions and other subjective assessments. In particular, management has identified several accounting policies that, due to the judgments, estimates and assumptions inherent in those policies, are critical to an understanding of Banner’s financial statements. These policies relate to (i) the methodology for the recognition of interest income, (ii) determination of the provision and allowance for loan and lease losses, (iii) the valuation of financial assets and liabilities recorded at fair value, including other-than-temporary impairment (OTTI) losses, (iv) the valuation of intangibles, such as core deposit intangibles and mortgage servicing rights, (v) the valuation of real estate held for sale and (vi) the valuation of or recognition of deferred tax assets and liabilities. These policies and judgments, estimates and assumptions are described in greater detail in subsequent notes to the Consolidated Financial Statements and Management’s Discussion and Analysis of Financial Condition and Results of Operations (Critical Accounting Policies) in our Annual Report on Form 10-K for the year ended December 31, 2012 filed with the Securities and Exchange Commission (SEC). Management believes that the judgments, estimates and assumptions used in the preparation of the financial statements are appropriate based on the factual circumstances at the time. However, given the sensitivity of the financial statements to these critical accounting policies, the use of other judgments, estimates and assumptions could result in material differences in the Company’s results of operations or financial condition. Further, subsequent changes in economic or market conditions could have a material impact on these estimates and the Company’s financial condition and operating results in future periods. The information included in this Form 10-Q should be read in conjunction with our Annual Report on Form 10-K for the year ended December 31, 2012 filed with the SEC (2012 Form 10-K). Interim results are not necessarily indicative of results for a full year.

BASIS OF PRESENTATION AND CRITICAL ACCOUNTING POLICIES

The accompanying unaudited consolidated financial statements include the accounts of Banner Corporation (the Company or Banner), a bank holding company incorporated in the State of Washington and its wholly-owned subsidiaries, Banner Bank and Islanders Bank (the Banks).

These unaudited consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (GAAP) for interim financial information and in accordance with the instructions to Form 10-Q and Article 10 of Regulation S-X as promulgated by the Securities and Exchange Commission (SEC). In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation of the financial position and results of operations for the periods presented have been included. Certain information and disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to the rules and regulations of the SEC. Certain reclassifications have been made to the 2012 Consolidated Financial Statements and/or schedules to conform to the 2013 presentation. These reclassifications may have affected certain ratios for the prior periods. The effect of these reclassifications is considered immaterial. All significant intercompany transactions and balances have been eliminated.

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect amounts reported in the financial statements. Various elements of the Company’s accounting policies, by their nature, are inherently subject to estimation techniques, valuation assumptions and other subjective assessments. In particular, management has identified several accounting policies that, due to the judgments, estimates and assumptions inherent in those policies, are critical to an understanding of Banner’s financial statements. These policies relate to (i) the methodology for the recognition of interest income, (ii) determination of the provision and allowance for loan and lease losses, (iii) the valuation of financial assets and liabilities recorded at fair value, including other-than-temporary impairment (OTTI) losses, (iv) the valuation of intangibles, such as core deposit intangibles and mortgage servicing rights, (v) the valuation of real estate held for sale and (vi) the valuation of or recognition of deferred tax assets and liabilities. These policies and judgments, estimates and assumptions are described in greater detail in subsequent notes to the Consolidated Financial Statements and Management’s Discussion and Analysis of Financial Condition and Results of Operations (Critical Accounting Policies) in our Annual Report on Form 10-K for the year ended December 31, 2012 filed with the Securities and Exchange Commission (SEC). Management believes that the judgments, estimates and assumptions used in the preparation of the financial statements are appropriate based on the factual circumstances at the time. However, given the sensitivity of the financial statements to these critical accounting policies, the use of other judgments, estimates and assumptions could result in material differences in the Company’s results of operations or financial condition. Further, subsequent changes in economic or market conditions could have a material impact on these estimates and the Company’s financial condition and operating results in future periods.

The information included in this Form 10-Q should be read in conjunction with our Annual Report on Form 10-K for the year ended December 31, 2012 filed with the SEC (2012 Form 10-K). Interim results are not necessarily indicative of results for a full year.