Significant Accounting Policies	9 Months Ended
Significant Accounting Policies	Sep. 30, 2023
Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	Basis of Presentation The accompanying unaudited consolidated financial statements of BOK Financial Corporation ("BOK Financial" or "the Company") 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 ("the Bank"), BOK Financial Securities, Inc., and BOK Financial Private Wealth, Inc. Operating divisions of the Bank include Bank of Albuquerque, Bank of Oklahoma, Bank of Texas, BOK Financial in Arizona, Arkansas, Colorado and Kansas/Missouri, BOK Financial Mortgage and the TransFund electronic funds network. Certain reclassifications have been made to conform to the current period presentation. The financial information should be read in conjunction with BOK Financial's 2022 Form 10-K filed with the Securities and Exchange Commission, which contains audited financial statements. Amounts presented as of December 31, 2022 have been derived from the audited financial statements included in BOK Financial's 2022 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 nine-month period ended September 30, 2023 are not necessarily indicative of the results that may be expected for the year ending December 31, 2023. Newly Adopted and Pending Accounting Policies Financial Accounting Standards Board ("FASB") FASB Accounting Standards Update No. 2022-02, Financial Instruments - Credit Losses (Topic 326): Troubled Debt Restructurings and Vintage Disclosures ("ASU 2022-02") On March 31, 2022, the FASB issued ASU 2022-02 which eliminates the accounting guidance on troubled debt restructurings ("TDRs") for creditors in ASC 310-40, while also no longer requiring an entity to consider renewals, modifications, and extensions that result from reasonably expected TDRs in their calculation of the allowance for credit losses. For receivables for which there has been a modification in their contractual cash flows, ASU 2022-02 requires disclosure, by class of financing receivable, of the types of modifications, the financial effects of those modifications, and the performance of these modified receivables, along with receivables that had a payment default during the current period and had modifications to the contractual cash flows within 12 months prior to the default. Further, ASU 2022-02 requires entities to disclose gross write-offs recorded in the current period by year of origination in the vintage disclosures on a year-to-date basis. ASU 2022-02 was effective for the Company January 1, 2023. Amendments related to TDR recognition and measurement and vintage disclosures were applied prospectively and are included in Note 4 to the consolidated financial statements. Adoption of this standard did not have a material effect on the Company's financial condition or results of operations. FASB Accounting Standards Update No. 2023-01, Leases (Topic 842): Common Control Arrangements ("ASU 2023-01") On March 27, 2023, the FASB issued ASU 2023-01 which, in part, amends the accounting for leasehold improvement in common-control arrangements. Under previous guidance, a lessee is generally required to amortize leasehold improvements that it owns over the shorter of the useful life of those improvements or the lease term. However, due to the nature of leasehold improvements made under leases between entities under common control, ASU 2023-01 requires a lessee in a common-control arrangement to amortize such leasehold improvements that it owns over the improvements' useful life to the common control group, regardless of the lease term. ASU 2023-01 is effective for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years. Adoption of ASU 2023-01 is not expected to have a material impact on the Company's financial statements. FASB Accounting Standards Update No. 2023-02, Investments - Equity Method and Joint Ventures (Topic 323): Accounting for Investments in Tax Credit Structures Using the Proportional Amortization Method ("ASU 2023-02")On March 29, 2023, the FASB issued ASU 2023-02 which amends previous guidance to allow entities to account for qualifying tax equity investments using the proportional amortization method regardless of the program giving rise to the related income tax credits, as opposed to only being allowed to apply this method to qualifying tax equity investments in low-income housing tax credit structures as was the case under previous guidance. ASU 2023-02 is effective for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years. On June 30, 2023, the Company early adopted ASU 2023-02 as of January 1, 2023 using the modified retrospective approach, which did not have a material impact on the Company's financial statements. The Company transitioned from the equity method of accounting and began applying the proportional amortization method of accounting to its qualifying new markets tax credit and historic tax credit investments in addition to its low income housing tax credit partnerships already subject to the proportional amortization method.