Basis of Presentation and Accounting Policies	6 Months Ended
Jun. 30, 2025
Accounting Policies [Abstract]
Basis of Presentation and Accounting Policies	BASIS OF PRESENTATION AND ACCOUNTING POLICIES Organization The accompanying unaudited consolidated financial statements were prepared in accordance with United States (U.S.) generally accepted accounting principles (GAAP) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, the statements do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation were included. The results of operations for the six months ended June 30, 2025 are not necessarily indicative of the results that may be expected for the year ending December 31, 2025. Certain items in prior periods were reclassified to conform to the current presentation. The accompanying unaudited financial statements should be read in conjunction with the consolidated financial statements and footnotes included in the Annual Report on Form 10-K of Comerica Incorporated and Subsidiaries (the Corporation) for the year ended December 31, 2024 (2024 Annual Report). Recently Issued Accounting Pronouncements In December 2023, the FASB issued ASU No. 2023-09 "Income Taxes (Topic 740): Improvements to Income Tax Disclosures" (ASU 2023-09). ASU 2023-09 requires additional annual disclosures including further disaggregation of information in the rate reconciliation, additional information for reconciling items meeting a quantitative threshold, further disaggregation of income taxes paid and other required disclosures. ASU 2023-09 is effective for the Corporation in the annual period beginning on January 1, 2025 and applied on a prospective basis with both early adoption and retrospective application permitted. The impact of ASU 2023-09 is not expected to be material to the Corporation's income tax disclosures. In November 2024, the FASB issued ASU No. 2024-03 "Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses" (ASU 2024-03). ASU 2024-03 requires additional interim and annual disclosures that further disaggregate certain expense captions into specified categories in a separate note to the financial statements, as well as certain qualitative information describing amounts not separately disaggregated. ASU 2024-03 is effective for the Corporation in the annual period beginning on January 1, 2027 and interim periods beginning on January 1, 2028 and can be applied on either a prospective or retrospective basis, with early adoption permitted. The Corporation is evaluating the impact of ASU 2024-03 to its disclosures.

The accompanying unaudited consolidated financial statements were prepared in accordance with United States (U.S.) generally accepted accounting principles (GAAP) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, the statements do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation were included. The results of operations for the six months ended June 30, 2025 are not necessarily indicative of the results that may be expected for the year ending December 31, 2025. Certain items in prior periods were reclassified to conform to the current presentation. The accompanying unaudited financial statements should be read in conjunction with the consolidated financial statements and footnotes included in the Annual Report on Form 10-K of Comerica Incorporated and Subsidiaries (the Corporation) for the year ended December 31, 2024 (2024 Annual Report).

In December 2023, the FASB issued ASU No. 2023-09 "Income Taxes (Topic 740): Improvements to Income Tax Disclosures" (ASU 2023-09). ASU 2023-09 requires additional annual disclosures including further disaggregation of information in the rate reconciliation, additional information for reconciling items meeting a quantitative threshold, further disaggregation of income taxes paid and other required disclosures. ASU 2023-09 is effective for the Corporation in the annual period beginning on January 1, 2025 and applied on a prospective basis with both early adoption and retrospective application permitted. The impact of ASU 2023-09 is not expected to be material to the Corporation's income tax disclosures.

In November 2024, the FASB issued ASU No. 2024-03 "Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses" (ASU 2024-03). ASU 2024-03 requires additional interim and annual disclosures that further disaggregate certain expense captions into specified categories in a separate note to the financial statements, as well as certain qualitative information describing amounts not separately disaggregated. ASU 2024-03 is effective for the Corporation in the annual period beginning on January 1, 2027 and interim periods beginning on January 1, 2028 and can be applied on either a prospective or retrospective basis, with early adoption permitted. The Corporation is evaluating the impact of ASU 2024-03 to its disclosures.