Summary of Significant Accounting Policies	9 Months Ended
Sep. 30, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation Bank of Hawaii Corporation (the “Parent”) is a Delaware corporation and a bank holding company headquartered in Honolulu, Hawaii. Bank of Hawaii Corporation and its subsidiaries (collectively, the “Company”) provide a broad range of financial products and services to customers in Hawaii, Guam, and other Pacific Islands. The Parent’s principal operating subsidiary is Bank of Hawaii (the “Bank”). All significant intercompany accounts and transactions have been eliminated in consolidation. The accompanying unaudited consolidated financial statements of the Company have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and accompanying notes required by GAAP for complete financial statements. In the opinion of management, the consolidated financial statements reflect normal recurring adjustments necessary for a fair presentation of the results for the interim periods. Certain prior period information has been reclassified to conform to the current period presentation. These statements should be read in conjunction with the audited consolidated financial statements and related notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2014. Operating results for the interim periods disclosed herein are not necessarily indicative of the results that may be expected for the year ending December 31, 2015. Use of Estimates in the Preparation of Financial Statements The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts in the financial statements and accompanying notes. Actual results may differ from those estimates and such differences could be material to the financial statements. Accounting Standards Adopted in 2015 In January 2014, the FASB issued ASU No. 2014-01, "Accounting for Investments in Qualified Affordable Housing Projects." ASU No. 2014-01 permits reporting entities to make an accounting policy election to account for their investments in qualified affordable housing projects using the proportional amortization method if certain conditions are met. Under the proportional amortization method, an entity amortizes the initial cost of the investment in proportion to the tax credits and other tax benefits received and recognizes the net investment performance in the income statement as a component of income tax expense. This new guidance also requires new disclosures for all investors in these projects (see Note 5 to the Consolidated Financial Statements). The Company adopted ASU No. 2014-01 effective January 1, 2015. Upon adoption, the guidance must be applied retrospectively to all periods presented. However, entities that used the effective yield method to account for investments in these projects before adoption may continue to do so for these pre-existing investments. Prior to adoption of ASU No. 2014-01, the Company accounted for such investments using the effective yield method and continued to do so for these pre-existing investments after adopting ASU No. 2014-01. The Company expects future investments to meet the criteria required for the proportional amortization method and plans to make such an accounting policy election. There were no new investments being amortized since the adoption of ASU No. 2014-01 on January 1, 2015, and therefore, the adoption of ASU No. 2014-01 has not had a material impact on the Company's Consolidated Financial Statements. In January 2014, the FASB issued ASU No. 2014-04, "Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure." The objective of this guidance is to clarify when an in substance repossession or foreclosure occurs, that is, when a creditor should be considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan such that the loan receivable should be derecognized and the real estate property recognized. ASU No. 2014-04 states that an in substance repossession or foreclosure occurs, and a creditor is considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan, upon either: (1) the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure; or (2) the borrower conveying all interest in the residential real estate property to the creditor to satisfy that loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. Additionally, ASU No. 2014-04 requires interim and annual disclosure of both: (1) the amount of foreclosed residential real estate property held by the creditor; and (2) the recorded investment in consumer mortgage loans collateralized by residential real estate property that are in the process of foreclosure according to local requirements of the applicable jurisdiction. The Company adopted ASU No. 2014-04 effective January 1, 2015. The adoption of ASU No. 2014-04 did not have a material impact on the Company's Consolidated Financial Statements. In June 2014, the FASB issued ASU No. 2014-11, "Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures." The new guidance aligns the accounting for repurchase-to-maturity transactions and repurchase agreements executed as repurchase financings with the accounting for other typical repurchase agreements. Going forward, these transactions would all be accounted for as secured borrowings. The guidance eliminates sale accounting for repurchase-to-maturity transactions and supersedes the guidance under which a transfer of a financial asset and a contemporaneous repurchase financing could be accounted for on a combined basis as a forward agreement, which has resulted in outcomes referred to as off-balance-sheet accounting. The amendments in the ASU require a new disclosure for transactions economically similar to repurchase agreements in which the transferor retains substantially all of the exposure to the economic return on the transferred financial assets throughout the term of the transaction. The amendments in the ASU also require expanded disclosures, effective June 30, 2015, about the nature of collateral pledged in repurchase agreements and similar transactions accounted for as secured borrowings (see Note 6 to the Consolidated Financial Statements). The Company adopted the amendments in this ASU effective January 1, 2015. As of September 30, 2015, all of the Company's repurchase agreements were typical in nature (i.e., not repurchase-to-maturity transactions or repurchase agreements executed as a repurchase financing) and are accounted for as secured borrowings. As such, the adoption of ASU No. 2014-11 did not have a material impact on the Company's Consolidated Financial Statements. In June 2014, the FASB issued ASU No. 2014-12, "Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period." The amendments in the ASU require that a performance target that affects vesting and that could be achieved after the requisite service period be treated as a performance condition. A reporting entity should apply existing guidance in Topic 718, Compensation - Stock Compensation, as it relates to awards with performance conditions that affect vesting to account for such awards. The performance target should not be reflected in estimating the grant-date fair value of the award. However, compensation cost should be recognized in the period in which it becomes probable that the performance target will be achieved and should represent the compensation cost attributable to the period(s) for which the requisite service has already been rendered. If the performance target becomes probable of being achieved before the end of the requisite service period, the remaining unrecognized compensation cost should be recognized prospectively over the remaining requisite service period. The total amount of compensation cost recognized during and after the requisite service period should reflect the number of awards that are expected to vest and should be adjusted to reflect those awards that ultimately vest. The requisite service period ends when the employee can cease rendering service and still be eligible to vest in the award if the performance target is achieved. Entities may apply the amendments in this ASU either: (1) prospectively to all awards granted or modified after the effective date; or (2) retrospectively to all awards with performance targets that are outstanding as of the beginning of the earliest annual period presented in the financial statements and to all new or modified awards thereafter. The Company adopted ASU No. 2014-12 effective January 1, 2015. As of September 30, 2015, the Company did not have any share-based payment awards that included performance targets that could be achieved after the requisite service period. As such, the adoption of ASU No. 2014-12 did not have a material impact on the Company's Consolidated Financial Statements. In August 2014, the FASB issued ASU No. 2014-14, “Classification of Certain Government-Guaranteed Mortgage Loans upon Foreclosure.” The objective of this guidance is to reduce diversity in practice related to how creditors classify government-guaranteed mortgage loans, including FHA and VA guaranteed loans, upon foreclosure. Some creditors reclassify those loans to real estate consistent with other foreclosed loans that do not have guarantees; others reclassify the loans to other receivables. The amendments in this guidance require that a mortgage loan be derecognized and that a separate other receivable be recognized upon foreclosure if the following conditions are met: (1) the loan has a government guarantee that is not separable from the loan before foreclosure; (2) at the time of foreclosure, the creditor has the intent to convey the real estate property to the guarantor and make a claim on the guarantee, and the creditor has the ability to recover under that claim; and (3) at the time of foreclosure, any amount of the claim that is determined on the basis of the fair value of the real estate is fixed. Upon foreclosure, the separate other receivable should be measured based on the amount of the loan balance (principal and interest) expected to be recovered from the guarantor. The Company adopted ASU No. 2014-14 effective January 1, 2015. The adoption of ASU No. 2014-14 did not have a material impact on the Company's Consolidated Financial Statements. Accounting Standards Pending Adoption In May 2014, the FASB and the International Accounting Standards Board (the "IASB") jointly issued a comprehensive new revenue recognition standard that will supersede nearly all existing revenue recognition guidance under GAAP and International Financial Reporting Standards ("IFRS"). Previous revenue recognition guidance in GAAP comprised broad revenue recognition concepts together with numerous revenue requirements for particular industries or transactions, which sometimes resulted in different accounting for economically similar transactions. In contrast, IFRS provided limited revenue recognition guidance and, consequently, could be difficult to apply to complex transactions. Accordingly, the FASB and the IASB initiated a joint project to clarify the principles for recognizing revenue and to develop a common revenue standard for U.S. GAAP and IFRS that would: (1) remove inconsistencies and weaknesses in revenue requirements; (2) provide a more robust framework for addressing revenue issues; (3) improve comparability of revenue recognition practices across entities, industries, jurisdictions, and capital markets; (4) provide more useful information to users of financial statements through improved disclosure requirements; and (5) simplify the preparation of financial statements by reducing the number of requirements to which an entity must refer. To meet those objectives, the FASB issued ASU No. 2014-09, "Revenue from Contracts with Customers." The standard’s core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. In doing so, companies generally will be required to use more judgment and make more estimates than under current guidance. These may include 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. The standard was initially effective for public entities for interim and annual reporting periods beginning after December 15, 2016; early adoption is not permitted. However, in August 2015, the FASB issued ASU No. 2015-14, "Revenue from Contracts with Customers - Deferral of the Effective Date" which defers the effective date by one year (i.e., interim and annual reporting periods beginning after December 15, 2017). Early adoption is permitted, but not before the original effective date (i.e., interim and annual reporting periods beginning after December 15, 2016). 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 and will be closely monitoring developments and additional guidance to determine the potential impact the new standard will have on the Company's Consolidated Financial Statements. In February 2015, the FASB issued ASU No. 2015-02, “Amendments to the Consolidation Analysis.” This ASU affects reporting entities that are required to evaluate whether they should consolidate certain legal entities. Specifically, the amendments: (1) modify the evaluation of whether limited partnerships and similar legal entities are variable interest entities (“VIEs”) or voting interest entities; (2) eliminate the presumption that a general partner should consolidate a limited partnership; (3) affect the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships; and (4) provide a scope exception from consolidation guidance for reporting entities with interests in legal entities that are required to comply with or operate in accordance with requirements that are similar to those in Rule 2a-7 of the Investment Company Act of 1940 for registered money market funds. ASU No. 2015-02 is effective for interim and annual reporting periods beginning after December 15, 2015. The adoption of ASU No. 2015-02 is not expected to have a material impact on the Company's Consolidated Financial Statements. In April 2015, the FASB issued ASU No. 2015-05, “Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement.” This ASU provides guidance to customers 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 new guidance does not change the accounting for a customer’s accounting for service contracts. ASU No. 2015-05 is effective for interim and annual reporting periods beginning after December 15, 2015. The Company’s current method of accounting for fees paid in a cloud computing arrangement is consistent with the accounting guidance provided by ASU No. 2015-05. Therefore, the adoption of ASU No. 2015-05 is not expected to have a material impact on the Company's Consolidated Financial Statements.

Summary of Significant Accounting Policies

Basis of Presentation

Bank of Hawaii Corporation (the “Parent”) is a Delaware corporation and a bank holding company headquartered in Honolulu, Hawaii. Bank of Hawaii Corporation and its subsidiaries (collectively, the “Company”) provide a broad range of financial products and services to customers in Hawaii, Guam, and other Pacific Islands. The Parent’s principal operating subsidiary is Bank of Hawaii (the “Bank”). All significant intercompany accounts and transactions have been eliminated in consolidation.

The accompanying unaudited consolidated financial statements of the Company have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and accompanying notes required by GAAP for complete financial statements. In the opinion of management, the consolidated financial statements reflect normal recurring adjustments necessary for a fair presentation of the results for the interim periods.

Certain prior period information has been reclassified to conform to the current period presentation.

These statements should be read in conjunction with the audited consolidated financial statements and related notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2014. Operating results for the interim periods disclosed herein are not necessarily indicative of the results that may be expected for the year ending December 31, 2015.

Use of Estimates in the Preparation of Financial Statements

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts in the financial statements and accompanying notes. Actual results may differ from those estimates and such differences could be material to the financial statements.

Accounting Standards Adopted in 2015

In January 2014, the FASB issued ASU No. 2014-01, "Accounting for Investments in Qualified Affordable Housing Projects." ASU No. 2014-01 permits reporting entities to make an accounting policy election to account for their investments in qualified affordable housing projects using the proportional amortization method if certain conditions are met. Under the proportional amortization method, an entity amortizes the initial cost of the investment in proportion to the tax credits and other tax benefits received and recognizes the net investment performance in the income statement as a component of income tax expense. This new guidance also requires new disclosures for all investors in these projects (see Note 5 to the Consolidated Financial Statements). The Company adopted ASU No. 2014-01 effective January 1, 2015. Upon adoption, the guidance must be applied retrospectively to all periods presented. However, entities that used the effective yield method to account for investments in these projects before adoption may continue to do so for these pre-existing investments. Prior to adoption of ASU No. 2014-01, the Company accounted for such investments using the effective yield method and continued to do so for these pre-existing investments after adopting ASU No. 2014-01. The Company expects future investments to meet the criteria required for the proportional amortization method and plans to make such an accounting policy election. There were no new investments being amortized since the adoption of ASU No. 2014-01 on January 1, 2015, and therefore, the adoption of ASU No. 2014-01 has not had a material impact on the Company's Consolidated Financial Statements.

In January 2014, the FASB issued ASU No. 2014-04, "Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure." The objective of this guidance is to clarify when an in substance repossession or foreclosure occurs, that is, when a creditor should be considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan such that the loan receivable should be derecognized and the real estate property recognized. ASU No. 2014-04 states that an in substance repossession or foreclosure occurs, and a creditor is considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan, upon either: (1) the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure; or (2) the borrower conveying all interest in the residential real estate property to the creditor to satisfy that loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. Additionally, ASU No. 2014-04 requires interim and annual disclosure of both: (1) the amount of foreclosed residential real estate property held by the creditor; and (2) the recorded investment in consumer mortgage loans collateralized by residential real estate property that are in the process of foreclosure according to local requirements of the applicable jurisdiction. The Company adopted ASU No. 2014-04 effective January 1, 2015. The adoption of ASU No. 2014-04 did not have a material impact on the Company's Consolidated Financial Statements.

In June 2014, the FASB issued ASU No. 2014-11, "Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures." The new guidance aligns the accounting for repurchase-to-maturity transactions and repurchase agreements executed as repurchase financings with the accounting for other typical repurchase agreements. Going forward, these transactions would all be accounted for as secured borrowings. The guidance eliminates sale accounting for repurchase-to-maturity transactions and supersedes the guidance under which a transfer of a financial asset and a contemporaneous repurchase financing could be accounted for on a combined basis as a forward agreement, which has resulted in outcomes referred to as off-balance-sheet accounting. The amendments in the ASU require a new disclosure for transactions economically similar to repurchase agreements in which the transferor retains substantially all of the exposure to the economic return on the transferred financial assets throughout the term of the transaction. The amendments in the ASU also require expanded disclosures, effective June 30, 2015, about the nature of collateral pledged in repurchase agreements and similar transactions accounted for as secured borrowings (see Note 6 to the Consolidated Financial Statements). The Company adopted the amendments in this ASU effective January 1, 2015. As of September 30, 2015, all of the Company's repurchase agreements were typical in nature (i.e., not repurchase-to-maturity transactions or repurchase agreements executed as a repurchase financing) and are accounted for as secured borrowings. As such, the adoption of ASU No. 2014-11 did not have a material impact on the Company's Consolidated Financial Statements.

In June 2014, the FASB issued ASU No. 2014-12, "Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period." The amendments in the ASU require that a performance target that affects vesting and that could be achieved after the requisite service period be treated as a performance condition. A reporting entity should apply existing guidance in Topic 718, Compensation - Stock Compensation, as it relates to awards with performance conditions that affect vesting to account for such awards. The performance target should not be reflected in estimating the grant-date fair value of the award. However, compensation cost should be recognized in the period in which it becomes probable that the performance target will be achieved and should represent the compensation cost attributable to the period(s) for which the requisite service has already been rendered. If the performance target becomes probable of being achieved before the end of the requisite service period, the remaining unrecognized compensation cost should be recognized prospectively over the remaining requisite service period. The total amount of compensation cost recognized during and after the requisite service period should reflect the number of awards that are expected to vest and should be adjusted to reflect those awards that ultimately vest. The requisite service period ends when the employee can cease rendering service and still be eligible to vest in the award if the performance target is achieved. Entities may apply the amendments in this ASU either: (1) prospectively to all awards granted or modified after the effective date; or (2) retrospectively to all awards with performance targets that are outstanding as of the beginning of the earliest annual period presented in the financial statements and to all new or modified awards thereafter. The Company adopted ASU No. 2014-12 effective January 1, 2015. As of September 30, 2015, the Company did not have any share-based payment awards that included performance targets that could be achieved after the requisite service period. As such, the adoption of ASU No. 2014-12 did not have a material impact on the Company's Consolidated Financial Statements.

In August 2014, the FASB issued ASU No. 2014-14, “Classification of Certain Government-Guaranteed Mortgage Loans upon Foreclosure.” The objective of this guidance is to reduce diversity in practice related to how creditors classify government-guaranteed mortgage loans, including FHA and VA guaranteed loans, upon foreclosure. Some creditors reclassify those loans to real estate consistent with other foreclosed loans that do not have guarantees; others reclassify the loans to other receivables. The amendments in this guidance require that a mortgage loan be derecognized and that a separate other receivable be recognized upon foreclosure if the following conditions are met: (1) the loan has a government guarantee that is not separable from the loan before foreclosure; (2) at the time of foreclosure, the creditor has the intent to convey the real estate property to the guarantor and make a claim on the guarantee, and the creditor has the ability to recover under that claim; and (3) at the time of foreclosure, any amount of the claim that is determined on the basis of the fair value of the real estate is fixed. Upon foreclosure, the separate other receivable should be measured based on the amount of the loan balance (principal and interest) expected to be recovered from the guarantor. The Company adopted ASU No. 2014-14 effective January 1, 2015. The adoption of ASU No. 2014-14 did not have a material impact on the Company's Consolidated Financial Statements.

Accounting Standards Pending Adoption

In May 2014, the FASB and the International Accounting Standards Board (the "IASB") jointly issued a comprehensive new revenue recognition standard that will supersede nearly all existing revenue recognition guidance under GAAP and International Financial Reporting Standards ("IFRS"). Previous revenue recognition guidance in GAAP comprised broad revenue recognition concepts together with numerous revenue requirements for particular industries or transactions, which sometimes resulted in different accounting for economically similar transactions. In contrast, IFRS provided limited revenue recognition guidance and, consequently, could be difficult to apply to complex transactions. Accordingly, the FASB and the IASB initiated a joint project to clarify the principles for recognizing revenue and to develop a common revenue standard for U.S. GAAP and IFRS that would: (1) remove inconsistencies and weaknesses in revenue requirements; (2) provide a more robust framework for addressing revenue issues; (3) improve comparability of revenue recognition practices across entities, industries, jurisdictions, and capital markets; (4) provide more useful information to users of financial statements through improved disclosure requirements; and (5) simplify the preparation of financial statements by reducing the number of requirements to which an entity must refer. To meet those objectives, the FASB issued ASU No. 2014-09, "Revenue from Contracts with Customers." The standard’s core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. In doing so, companies generally will be required to use more judgment and make more estimates than under current guidance. These may include 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. The standard was initially effective for public entities for interim and annual reporting periods beginning after December 15, 2016; early adoption is not permitted. However, in August 2015, the FASB issued ASU No. 2015-14, "Revenue from Contracts with Customers - Deferral of the Effective Date" which defers the effective date by one year (i.e., interim and annual reporting periods beginning after December 15, 2017). Early adoption is permitted, but not before the original effective date (i.e., interim and annual reporting periods beginning after December 15, 2016). 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 and will be closely monitoring developments and additional guidance to determine the potential impact the new standard will have on the Company's Consolidated Financial Statements.

In February 2015, the FASB issued ASU No. 2015-02, “Amendments to the Consolidation Analysis.” This ASU affects reporting entities that are required to evaluate whether they should consolidate certain legal entities. Specifically, the amendments: (1) modify the evaluation of whether limited partnerships and similar legal entities are variable interest entities (“VIEs”) or voting interest entities; (2) eliminate the presumption that a general partner should consolidate a limited partnership; (3) affect the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships; and (4) provide a scope exception from consolidation guidance for reporting entities with interests in legal entities that are required to comply with or operate in accordance with requirements that are similar to those in Rule 2a-7 of the Investment Company Act of 1940 for registered money market funds. ASU No. 2015-02 is effective for interim and annual reporting periods beginning after December 15, 2015. The adoption of ASU No. 2015-02 is not expected to have a material impact on the Company's Consolidated Financial Statements.

In April 2015, the FASB issued ASU No. 2015-05, “Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement.” This ASU provides guidance to customers 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 new guidance does not change the accounting for a customer’s accounting for service contracts. ASU No. 2015-05 is effective for interim and annual reporting periods beginning after December 15, 2015. The Company’s current method of accounting for fees paid in a cloud computing arrangement is consistent with the accounting guidance provided by ASU No. 2015-05. Therefore, the adoption of ASU No. 2015-05 is not expected to have a material impact on the Company's Consolidated Financial Statements.