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Significant accounting policies | 9 Months Ended
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Sep. 30, 2024
Accounting Policies [Abstract] |
Significant accounting policies | The consolidated interim financial statements of the Company were compiled in accordance with GAAP using the accounting policies set forth in note 1 of Notes to Financial Statements included in M&T's 2023 Annual Report, except as described in the following table. The financial statements contain all adjustments which are, in the opinion of management, necessary for a fair statement of the Company's financial position, results of operations and cash flows for the interim periods presented. Recent accounting developments
| Standard |  |  | Description |  |  | Required date of adoption |  |  | Effect on consolidated financial statements |
| Standards Adopted in 2024 |
| Accounting for Investments in Tax Credit Structures Using the Proportional Amortization Method |  |  | The amendments permit an election to account for tax equity investments, regardless of the tax credit program from which the income tax credits are received, using the proportional amortization method if certain conditions are met. Under the proportional amortization method, the initial cost of the investment is amortized in proportion to the income tax credits and other income tax benefits received and the net amortization and income tax credits and other income tax benefits are recognized in the income statement as a component of income tax expense (benefit). |  |  | January 1, 2024 |  |  | As described in note 12, the Company adopted the amended guidance effective January 1, 2024 using a modified retrospective transition. The guidance did not have a material impact on the Company's consolidated financial statements. |

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- Definition The entire disclosure for all significant accounting policies of the reporting entity. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147483426/235-10-50-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 235 -Name Accounting Standards Codification -Publisher FASB -URI https://asc.fasb.org/235/tableOfContent + Details
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