Basis Of Presentation And Accounting Policies	9 Months Ended
Sep. 30, 2011
Basis Of Presentation And Accounting Policies
Basis Of Presentation And Accounting Policies	NOTE 1 – BASIS OF PRESENTATION AND ACCOUNTING POLICIES The accompanying unaudited consolidated financial statements were prepared in accordance with 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 nine months ended September 30, 2011 are not necessarily indicative of the results that may be expected for the year ending December 31, 2011. Certain items in prior periods were reclassified to conform to the current presentation. For further information, refer to the consolidated financial statements and footnotes thereto included in the Annual Report of Comerica Incorporated and Subsidiaries (the Corporation) on Form 10-K for the year ended December 31, 2010. Recently Adopted Accounting Pronouncements In the third quarter 2011, the Corporation adopted Financial Accounting Standards Board (FASB) Accounting Standards Update (ASU) No. 2011-02, "Receivables (Topic 310): A Creditor's Determination of Whether a Restructuring is a Troubled Debt Restructuring," (ASU 2011-02), which clarifies existing guidance used by creditors to determine when a modification represents a troubled debt restructuring (TDR). As a result, the Corporation reassessed loan restructurings that occurred on or after January 1, 2011 to identify modifications that would be considered TDRs as a result of these clarifications. The Corporation identified additional TDRs of $9 million as a result of the reassessment. Impairment on these loans was previously measured as part of a homogeneous pool of loans with similar risk characteristics. Since these modifications are considered TDRs, specific allowances were established for these loans based on an individual assessment of impairment. The additional allowance associated with these loans was $1 million, compared to the allowance previously measured as part of a homogeneous pool of loans. At September 30, 2011, the allowance for credit losses associated with these loan balances was $4 million. Pending Accounting Pronouncements In September 2011, the FASB issued ASU No. 2011-08, "Intangibles – Goodwill and Other (Topic 350): Testing Goodwill for Impairment," (ASU 2011-08). The Corporation will adopt ASU 2011-08, which allows companies to use a qualitative approach to test goodwill for impairment, in its consolidated financial statements for the year ended December 30, 2011. The provisions of ASU 2011-08 give companies the option to first assess qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount as a basis for determining the need to perform step one of the annual test for goodwill impairment. The adoption of ASU 2011-08 will not have any effect on the Corporation's financial condition and results of operations. In June 2011, the FASB issued ASU No. 2011-05, "Comprehensive Income (Topic 220): Presentation of Comprehensive Income," (ASU 2011-05). The Corporation will adopt ASU 2011-05, which revises the presentation of comprehensive income in the financial statements, in the first quarter 2012. The provisions of ASU 2011-05 give companies the option to present total comprehensive income, components of net income, and components of other comprehensive income either in a single continuous statement of comprehensive income or in two separate but consecutive statements. While the provisions of ASU 2011-05 will amend the presentation of comprehensive income, the adoption of ASU 2011-05 will not have any effect on the Corporation's financial condition and results of operations. In May 2011, the FASB issued ASU No. 2011-04, "Fair Value Measurement (Topic 820): Amendments to Achieve Common Fair Value Measurement and Disclosure Requirements in U.S. GAAP and IFRSs," (ASU 2011-04). The Corporation will adopt ASU 2011-04, which generally aligns the principles of fair value measurements with International Financial Reporting Standards (IFRSs), in the first quarter 2012. The provisions of ASU 2011-04 clarify the application of existing fair value measurement requirements, and expand the disclosure requirements for fair value measurements. While the provisions of ASU 2011-04 will increase the Corporation's fair value disclosures the Corporation does not expect the adoption of ASU 2011-04 to have any effect on the Corporation's financial condition and results of operations.

Basis Of Presentation And Accounting Policies

9 Months Ended

Sep. 30, 2011

Basis Of Presentation And Accounting Policies

Basis Of Presentation And Accounting Policies

NOTE 1 – BASIS OF PRESENTATION AND ACCOUNTING POLICIES

The accompanying unaudited consolidated financial statements were prepared in accordance with 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 nine months ended September 30, 2011 are not necessarily indicative of the results that may be expected for the year ending December 31, 2011. Certain items in prior periods were reclassified to conform to the current presentation. For further information, refer to the consolidated financial statements and footnotes thereto included in the Annual Report of Comerica Incorporated and Subsidiaries (the Corporation) on Form 10-K for the year ended December 31, 2010.

Recently Adopted Accounting Pronouncements

In the third quarter 2011, the Corporation adopted Financial Accounting Standards Board (FASB) Accounting Standards Update (ASU) No. 2011-02, "Receivables (Topic 310): A Creditor's Determination of Whether a Restructuring is a Troubled Debt Restructuring," (ASU 2011-02), which clarifies existing guidance used by creditors to determine when a modification represents a troubled debt restructuring (TDR). As a result, the Corporation reassessed loan restructurings that occurred on or after January 1, 2011 to identify modifications that would be considered TDRs as a result of these clarifications. The Corporation identified additional TDRs of $9 million as a result of the reassessment. Impairment on these loans was previously measured as part of a homogeneous pool of loans with similar risk characteristics. Since these modifications are considered TDRs, specific allowances were established for these loans based on an individual assessment of impairment. The additional allowance associated with these loans was $1 million, compared to the allowance previously measured as part of a homogeneous pool of loans. At September 30, 2011, the allowance for credit losses associated with these loan balances was $4 million.

Pending Accounting Pronouncements

In September 2011, the FASB issued ASU No. 2011-08, "Intangibles – Goodwill and Other (Topic 350): Testing Goodwill for Impairment," (ASU 2011-08). The Corporation will adopt ASU 2011-08, which allows companies to use a qualitative approach to test goodwill for impairment, in its consolidated financial statements for the year ended December 30, 2011. The provisions of ASU 2011-08 give companies the option to first assess qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount as a basis for determining the need to perform step one of the annual test for goodwill impairment. The adoption of ASU 2011-08 will not have any effect on the Corporation's financial condition and results of operations.

In June 2011, the FASB issued ASU No. 2011-05, "Comprehensive Income (Topic 220): Presentation of Comprehensive Income," (ASU 2011-05). The Corporation will adopt ASU 2011-05, which revises the presentation of comprehensive income in the financial statements, in the first quarter 2012. The provisions of ASU 2011-05 give companies the option to present total comprehensive income, components of net income, and components of other comprehensive income either in a single continuous statement of comprehensive income or in two separate but consecutive statements. While the provisions of ASU 2011-05 will amend the presentation of comprehensive income, the adoption of ASU 2011-05 will not have any effect on the Corporation's financial condition and results of operations.

In May 2011, the FASB issued ASU No. 2011-04, "Fair Value Measurement (Topic 820): Amendments to Achieve Common Fair Value Measurement and Disclosure Requirements in U.S. GAAP and IFRSs," (ASU 2011-04). The Corporation will adopt ASU 2011-04, which generally aligns the principles of fair value measurements with International Financial Reporting Standards (IFRSs), in the first quarter 2012. The provisions of ASU 2011-04 clarify the application of existing fair value measurement requirements, and expand the disclosure requirements for fair value measurements. While the provisions of ASU 2011-04 will increase the Corporation's fair value disclosures the Corporation does not expect the adoption of ASU 2011-04 to have any effect on the Corporation's financial condition and results of operations.