Significant Accounting Policies	3 Months Ended
Mar. 31, 2026
Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	Significant Accounting Policies Basis of Presentation The accompanying unaudited consolidated financial statements of BOK Financial have been prepared in accordance with accounting principles for interim financial information generally accepted in the United States and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. The unaudited consolidated financial statements include accounts of BOK Financial and its subsidiaries, principally BOKF, NA, BOK Financial Securities, Inc., BOK Financial Private Wealth, Inc., and Cavanal Hill Distributors, Inc. Operating divisions of BOKF, NA include Bank of Albuquerque, Bank of Oklahoma, Bank of Texas, and BOK Financial in Arizona, Arkansas, Colorado, and Kansas/Missouri. BOKF, NA also operates the TransFund electronic funds network, BOK Financial Mortgage, and Cavanal Hill Investment Management. Certain reclassifications have been made to conform to the current period presentation. The financial information should be read in conjunction with BOK Financial's 2025 Form 10-K filed with the Securities and Exchange Commission, which contains audited financial statements. Amounts presented as of December 31, 2025, have been derived from the audited financial statements included in BOK Financial's 2025 Form 10-K but do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. Operating results for the three-month period ended March 31, 2026, are not necessarily indicative of the results that may be expected for the year ending December 31, 2026. Newly Adopted and Pending Accounting Policies Financial Accounting Standards Board FASB ASU 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses The FASB issued ASU 2024-03 on November 4, 2024, which amends the disclosure of certain costs and expenses. The amendments intend to bring improvement by requiring further disaggregation of expenses that are not already required to be disclosed in the notes to the financial statements at interim and annual reporting periods. ASU 2024-03 is effective for annual reporting periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. The Company is currently assessing the impact ASU 2024-03 will have on its expense disclosures. FASB ASU 2025-05, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets The FASB issued ASU 2025-05 on July 30, 2025, which provides a practical expedient related to the estimation of expected credit losses for current accounts receivable and current contract assets arising from transactions accounted for under Topic 606, Revenue from Contracts with Customers. Under the practical expedient, entities may assume current conditions as of the balance sheet date remain unchanged for the remaining life of the asset when developing reasonable and supportable forecasts. ASU 2025-05 is effective for annual reporting periods beginning after December 15, 2025, and interim reporting periods within those annual reporting periods, with early adoption permitted. Adoption of ASU 2025-05 did not have a material impact on the Company's financial statements or disclosures. FASB ASU 2025-06, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software The FASB issued ASU 2025-06 on September 18, 2025, which modernizes the accounting for internal-use software costs. This amendment eliminates accounting consideration of software project development stages and clarifies the threshold applied to begin capitalizing costs. ASU 2025-06 is effective for annual reporting periods beginning after December 15, 2027, and interim reporting periods within those annual reporting periods, with early adoption permitted. The Company is currently assessing the impact ASU 2025-06 will have on its internal software costs. FASB ASU 2025-08, Financial Instruments—Credit Losses (Topic 326): Purchased Loans The FASB issued ASU 2025-08 on November 12, 2025, which clarifies and simplifies the accounting for credit losses on purchased loans under CECL, specifically how entities account for expected credit losses at acquisition and subsequent changes in those expectations. Under this new guidance, loans acquired without credit deterioration and deemed “seasoned” will be considered purchased seasoned loans and accounted for using the gross-up approach at acquisition (i.e., record the loan at its purchase price and separately record an allowance for expected credit losses). Seasoned loans include all loans acquired in a business combination that do not have “more-than-insignificant” deterioration of credit quality since origination, as well as loans purchased at least 90 days after origination where the purchaser was not involved in the origination of the loans. ASU 2025-08 is effective for all entities for annual reporting periods beginning after December 15, 2026, and interim reporting periods within those annual reporting periods. The Company is currently assessing the impact ASU 2025-08 will have on its purchased loans. FASB ASU 2025-09, Derivatives and Hedging (Topic 815): Hedge Accounting Improvements The FASB issued ASU 2025-09 on November 25, 2025, which enables entities to apply hedge accounting to a greater number of highly effective economic hedges in the following five areas: (1) similar risk assessment for cash flow hedges, (2) hedging forecasted interest payments on choose-your-rate debt instruments, (3) cash flow hedges of nonfinancial forecasted transactions, (4) net written options as hedging instruments, and (5) foreign-currency-denominated debt instrument as hedging instrument and hedged item (dual hedge). ASU 2025-09 is effective for all entities for annual reporting periods beginning after December 15, 2026, and interim reporting periods within those annual reporting periods. The Company is currently assessing the impact ASU 2025-08 will have on its disclosures. FASB ASU 2025-11, Interim Reporting (Topic 270) The FASB issued ASU 2025-11 on December 8, 2025, which is intended to improve the navigability of the guidance in ASC 270 and clarify when it applies. Under the amendments, an entity is subject to ASC 270 if it provides interim financial statements and notes in accordance with GAAP. ASU 2025-11 also addresses the form and content of such financial statements, interim disclosures requirements, and establishes a principle under which an entity must disclose events since the end of the last annual reporting period that have a material impact on the entity. ASU 2025-11 is effective for interim reporting periods within annual reporting periods beginning after December 15, 2027, and early adoption is permitted. The Company is currently assessing the impact ASU 2025-11 will have on the Company's financial statements.

The accompanying unaudited consolidated financial statements of BOK Financial have been prepared in accordance with accounting principles for interim financial information generally accepted in the United States and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included.

The unaudited consolidated financial statements include accounts of BOK Financial and its subsidiaries, principally BOKF, NA, BOK Financial Securities, Inc., BOK Financial Private Wealth, Inc., and Cavanal Hill Distributors, Inc. Operating divisions of BOKF, NA include Bank of Albuquerque, Bank of Oklahoma, Bank of Texas, and BOK Financial in Arizona, Arkansas, Colorado, and Kansas/Missouri. BOKF, NA also operates the TransFund electronic funds network, BOK Financial Mortgage, and Cavanal Hill Investment Management.

The financial information should be read in conjunction with BOK Financial's 2025 Form 10-K filed with the Securities and Exchange Commission, which contains audited financial statements. Amounts presented as of December 31, 2025, have been derived from the audited financial statements included in BOK Financial's 2025 Form 10-K but do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. Operating results for the three-month period ended March 31, 2026, are not necessarily indicative of the results that may be expected for the year ending December 31, 2026.

The FASB issued ASU 2024-03 on November 4, 2024, which amends the disclosure of certain costs and expenses. The amendments intend to bring improvement by requiring further disaggregation of expenses that are not already required to be disclosed in the notes to the financial statements at interim and annual reporting periods. ASU 2024-03 is effective for annual reporting periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. The Company is currently assessing the impact ASU 2024-03 will have on its expense disclosures.

The FASB issued ASU 2025-05 on July 30, 2025, which provides a practical expedient related to the estimation of expected credit losses for current accounts receivable and current contract assets arising from transactions accounted for under Topic 606, Revenue from Contracts with Customers. Under the practical expedient, entities may assume current conditions as of the balance sheet date remain unchanged for the remaining life of the asset when developing reasonable and supportable forecasts. ASU 2025-05 is effective for annual reporting periods beginning after December 15, 2025, and interim reporting periods within those annual reporting periods, with early adoption permitted. Adoption of ASU 2025-05 did not have a material impact on the Company's financial statements or disclosures.

The FASB issued ASU 2025-06 on September 18, 2025, which modernizes the accounting for internal-use software costs. This amendment eliminates accounting consideration of software project development stages and clarifies the threshold applied to begin capitalizing costs. ASU 2025-06 is effective for annual reporting periods beginning after December 15, 2027, and interim reporting periods within those annual reporting periods, with early adoption permitted. The Company is currently assessing the impact ASU 2025-06 will have on its internal software costs.

The FASB issued ASU 2025-08 on November 12, 2025, which clarifies and simplifies the accounting for credit losses on purchased loans under CECL, specifically how entities account for expected credit losses at acquisition and subsequent changes in those expectations. Under this new guidance, loans acquired without credit deterioration and deemed “seasoned” will be considered purchased seasoned loans and accounted for using the gross-up approach at acquisition (i.e., record the loan at its purchase price and separately record an allowance for expected credit losses). Seasoned loans include all loans acquired in a business combination that do not have “more-than-insignificant” deterioration of credit quality since origination, as well as loans purchased at least 90 days after origination where the purchaser was not involved in the origination of the loans. ASU 2025-08 is effective for all entities for annual reporting periods beginning after December 15, 2026, and interim reporting periods within those annual reporting periods. The Company is currently assessing the impact ASU 2025-08 will have on its purchased loans.

The FASB issued ASU 2025-09 on November 25, 2025, which enables entities to apply hedge accounting to a greater number of highly effective economic hedges in the following five areas: (1) similar risk assessment for cash flow hedges, (2) hedging forecasted interest payments on choose-your-rate debt instruments, (3) cash flow hedges of nonfinancial forecasted transactions, (4) net written options as hedging instruments, and (5) foreign-currency-denominated debt instrument as hedging instrument and hedged item (dual hedge). ASU 2025-09 is effective for all entities for annual reporting periods beginning after December 15, 2026, and interim reporting periods within those annual reporting periods. The Company is currently assessing the impact ASU 2025-08 will have on its disclosures.

The FASB issued ASU 2025-11 on December 8, 2025, which is intended to improve the navigability of the guidance in ASC 270 and clarify when it applies. Under the amendments, an entity is subject to ASC 270 if it provides interim financial statements and notes in accordance with GAAP. ASU 2025-11 also addresses the form and content of such financial statements, interim disclosures requirements, and establishes a principle under which an entity must disclose events since the end of the last annual reporting period that have a material impact on the entity. ASU 2025-11 is effective for interim reporting periods within annual reporting periods beginning after December 15, 2027, and early adoption is permitted. The Company is currently assessing the impact ASU 2025-11 will have on the Company's financial statements.