| Pay vs Performance Disclosure | 12 Months Ended |
| Dec. 31, 2022 USD ($) $ / shares | Dec. 31, 2021 USD ($) $ / shares | Dec. 31, 2020 USD ($) $ / shares |
| Pay vs Performance Disclosure [Table] | | | |
| Pay vs Performance [Table Text Block] | Average (3) Average (4) Value of Initial Fixed $100 Investment Based On: Year Summary (1) Compensation (2) Total (5) Peer (5) Net Income (6) (7) (a) (b) (c) (d) (e) (f) (g) (h) (i) 2022 8,733,364 7,563,916 2,734,143 1,891,070 107 97 1,151 6.83 2021 7,696,094 11,609,076 2,477,730 3,431,583 134 124 1,168 6.12 2020 5,014,099 1,865,997 1,892,565 1,817,386 83 89 497 5.14 | | |
| Company Selected Measure Name | MIP EPS | | |
| Named Executive Officers, Footnote [Text Block] | The dollar amounts reported in this column represent the amounts of total compensation reported for Mr. Farmer (our principal executive officer, or "PEO") for each corresponding year in the “Total” column of the Summary Compensation Table. Refer to “Summary Compensation Table.”The dollar amounts reported in this column represent the average of the amounts reported for Comerica's NEOs as a group (excluding Mr. Farmer, who has served as our CEO since April 2019) in the “Total” column of the Summary Compensation Table in each applicable year. The names of each of the NEOs (excluding Mr. Farmer) included for purposes of calculating the average amounts in each applicable year are as follows: (i) for 2022, Messrs. Herzog, Sefzik, Oberg and Buchanan and Ms. Crespi; (ii) for 2021, Messrs. Herzog, Buchanan, Sefzik and Oberg; and (iii) for 2020, Messrs. Herzog, Carr and Buchanan and Ms. Crespi. | | |
| Peer Group Issuers, Footnote [Text Block] | Total Shareholder Return ("TSR") is cumulative for the measurement periods beginning on December 31, 2019 and ending on the last fiscal day in 2022, 2021 and 2020, respectively, calculated in accordance with Item 201(e) of Regulation S-K. “Peer Group” represents the KBW Bank Index for each year disclosed in the table. | | |
| PEO Total Compensation Amount | $ 8,733,364 | $ 7,696,094 | $ 5,014,099 |
| PEO Actually Paid Compensation Amount | $ 7,563,916 | 11,609,076 | 1,865,997 |
| Adjustment To PEO Compensation, Footnote [Text Block] | The dollar amounts reported in this column represent the amount of “compensation actually paid” to Mr. Farmer, as computed in accordance with Item 402(v) of Regulation S-K. The dollar amounts do not reflect the actual amount of compensation earned by or paid to Mr. Farmer during the applicable year. In accordance with the requirements of Item 402(v) of Regulation S-K, the following adjustments were made to Mr. Farmer’s total compensation as reported in the Summary Compensation Table for each year to determine the compensation actually paid: Year Reported Summary Compensation Table Total for PEO Subtract: Reported Value of Equity Awards (a) ($) Add: Equity Award Adjustments (b) ($) Subtract: Reported Change in the Actuarial Present Value of Pension Benefits (c) ($) Add: Pension Benefit Adjustments (d) ($) Compensation Actually Paid to PEO 2022 8,733,364 4,281,205 3,162,544 187,153 136,366 7,563,916 2021 7,696,094 3,805,582 7,734,030 114,858 99,392 11,609,076 2020 5,014,099 3,188,716 149,175 158,455 49,894 1,865,997 a. The amounts included in this column represent the grant date fair value of equity awards, calculated as the sum of the amounts reported in the “Stock Awards” and “Option Awards” columns in the Summary Compensation Table for each applicable year. b. The equity award adjustments for each applicable year include the addition (or subtraction, as applicable) of the following: (i) the year-end fair value of any equity awards granted in the applicable year that are outstanding and unvested as of the end of the year; (ii) the amount of change as of the end of the applicable year (from the end of the prior fiscal year) in fair value of any awards granted in prior years that are outstanding and unvested as of the end of the applicable year; (iii) for awards that are granted and vest in the same applicable year, the fair value as of the vesting date; (iv) for awards granted in prior years that vest in the applicable year, the amount equal to the change as of the vesting date (from the end of the prior fiscal year) in fair value; (v) for awards granted in prior years that are determined to fail to meet the applicable vesting conditions during the applicable year, a deduction for the amount equal to the fair value at the end of the prior fiscal year; and (vi) the dollar value of any dividends or other earnings paid on stock or option awards in the applicable year prior to the vesting date that are not otherwise reflected in the fair value of such award or included in any other component of total compensation for the applicable year. The valuation assumptions used to calculate fair values did not materially differ from those disclosed at the time of grant. The amounts deducted or added in calculating the equity award adjustments are as follows: Year Year End Fair Value of Unvested Equity Awards Granted in the Year Year over Year Change in Fair Value of Outstanding and Unvested Equity Awards Fair Value as of Vesting Date of Equity Awards Granted and Vested in the Year Year over Year Change in Fair Value of Equity Awards Granted in Prior Years that Vested in the Year Fair Value at the End of the Prior Year of Equity Awards that Failed to Meet Vesting Conditions in the Year Value of Dividends or other Earnings Paid on Stock or Option Awards not Otherwise Reflected in Fair Value or Total Compensation Total Equity Award Adjustments 2022 3,749,103 (624,360) — 37,801 — — 3,162,544 2021 5,603,372 1,999,322 — 131,336 — — 7,734,030 2020 2,635,946 (2,065,535) — (421,236) — — 149,175 c. The amounts included in this column are the amounts reported in the “Change in Pension Value and Nonqualified Deferred Compensation Earnings” column of the Summary Compensation Table for the applicable year. d. The total pension benefit adjustments for each applicable year include the aggregate of two components: (i) the actuarially determined service cost for services rendered by Mr. Farmer during the applicable year (the “service cost”); and (ii) the entire cost of benefits granted in a plan amendment (or initiation) during the applicable year that is attributed by the benefit formula to services rendered in periods prior to the plan amendment or initiation (the “prior service cost”), in each case, calculated in accordance with U.S. GAAP. The amounts deducted or added in calculating the pension benefit adjustments are as follows: Year Service Cost Prior Service Cost Total Pension Benefit Adjustment 2022 136,366 — 136,366 2021 95,950 3,442 99,392 2020 49,894 — 49,894 | | |
| Non-PEO NEO Average Total Compensation Amount | $ 2,734,143 | 2,477,730 | 1,892,565 |
| Non-PEO NEO Average Compensation Actually Paid Amount | $ 1,891,070 | 3,431,583 | 1,817,386 |
| Adjustment to Non-PEO NEO Compensation Footnote [Text Block] | The dollar amounts reported in this column represent the average amount of “compensation actually paid” to the NEOs as a group (excluding Mr. Farmer), as computed in accordance with Item 402(v) of Regulation S-K. The dollar amounts do not reflect the actual average amount of compensation earned by or paid to the NEOs as a group (excluding Mr. Farmer) during the applicable year. In accordance with the requirements of Item 402(v) of Regulation S-K, the following adjustments were made to average total compensation for the NEOs as a group (excluding Mr. Farmer) as reported in the Summary Compensation Tables for each year to determine the compensation actually paid, using the same methodology described above in Note 2: Year Average Reported Summary Compensation Table Total for Non-PEO NEOs Subtract: Average Reported Value of Equity Awards ($) Add : Average Equity Award Adjustments (a) ($) Subtract: Average Reported Change in the Actuarial Present Value of Pension Benefits (b) ($) Add: Average Pension Benefit Adjustments (c) ($) Average Compensation Actually Paid to Non-PEO NEOs 2022 2,734,143 899,126 18,834 23,937 61,156 1,891,070 2021 2,477,730 911,371 1,800,780 27,476 91,920 3,431,583 2020 1,892,565 799,843 841,834 130,925 13,755 1,817,386 a. The amounts deducted or added in calculating the total average equity award adjustments are as set forth below. See Note 3 for the names of non-PEO NEOs included in the calculation for each fiscal year. Year Average Year End Fair Value of Unvested Year Equity Awards Granted in the Year Year over Year Average Change in Fair Value of Outstanding and Unvested Equity Awards Average Fair Value as of Vesting Date of Equity Awards Granted and Vested in the Year Average Year over Year Average Change in Fair Value of Equity Awards Granted in Prior Years that Vested in the Year Average Fair Value at the End of the Prior Year of Equity Awards that Failed to Meet Vesting Conditions in the Year Average Value of Dividends or other Earnings Paid on Stock or Option Awards not Otherwise Reflected in Fair Value or Total Compensation Total Average Equity Award Adjustments 2022 651,661 (184,686) — 14,219 (462,360) — 18,834 2021 1,341,915 421,124 — 37,741 — — 1,800,780 2020 1,139,640 (208,030) — (89,776) — — 841,834 b. The amounts included in this column are the average amounts reported for non-PEO NEOs in the “Change in Pension Value and Nonqualified Deferred Compensation Earnings” column of the Summary Compensation Table during each fiscal year. Pursuant to SEC rules, averages include negative changes reflected as "0". See Note 3 for the names of non-PEO NEOs included in the calculation for each fiscal year. c. The average amounts deducted or added in calculating the total pension benefit adjustments are as set forth below. See Note 3 for the names of non-PEO NEOs included in the calculation for each fiscal year. Year Average Service Cost Average Prior Service Cost Average Total Pension Benefit Adjustment 2022 61,156 — 61,156 2021 51,737 40,183 91,920 2020 13,755 — 13,755 | | |
| Compensation Actually Paid vs. Total Shareholder Return [Text Block] | As demonstrated by the following graph, the amount of compensation actually paid to Mr. Farmer and the average amount of compensation actually paid to Comerica’s NEOs as a group (excluding Mr. Farmer) are aligned with Comerica’s cumulative TSR over the three years presented in the table. Compensation actually paid is aligned with cumulative TSR over the period because a significant portion of the compensation actually paid to Mr. Farmer and to the other NEOs is comprised of equity awards. As described in more detail in the section “Compensation Discussion and Analysis,” Comerica aims for approximately 62% of the value of total compensation awarded to the NEOs to be comprised of equity awards, including restricted stock units, performance-based restricted stock units and stock options. | | |
| Compensation Actually Paid vs. Net Income [Text Block] | As demonstrated by the following table, the amount of compensation actually paid to Mr. Farmer and the average amount of compensation actually paid to Comerica’s NEOs as a group (excluding Mr. Farmer) is generally aligned with Comerica’s net income over the three years presented in the table. While Comerica does not specifically use net income as a performance measure in the overall executive compensation program, the measure of net income is correlated with the measure of MIP EPS, which the company does use for setting goals in Comerica’s short-term incentive compensation program, the AEI. As described in more detail in the section “Compensation Discussion and Analysis,” Comerica aims for approximately 23% of the value of total compensation awarded to the NEOs to consist of amounts determined under the AEI. | | |
| Compensation Actually Paid vs. Company Selected Measure [Text Block] | As demonstrated by the following graph, the amount of compensation actually paid to Mr. Farmer and the average amount of compensation actually paid to Comerica’s NEOs as a group (excluding Mr. Farmer) is generally aligned with Comerica’s MIP EPS over the three years presented in the table. While Comerica uses numerous financial and non-financial performance measures for the purpose of evaluating performance for Comerica’s compensation programs, Comerica has determined that MIP EPS is the financial performance measure that, in Comerica’s assessment, represents the most important performance measure used by Comerica to link compensation actually paid to its NEOs, for the most recently completed fiscal year, to Comerica performance. Comerica utilizes MIP EPS when setting goals for the AEI. As described in more detail in the section “Compensation Discussion and Analysis,” Comerica aims for approximately 23% of the value of total compensation awarded to the NEOs to consist of amounts determined under the AEI and approximately 62% of the value of total compensation awarded to the NEOs to be comprised of equity awards, including restricted stock units, performance-based restricted stock units and stock options. | | |
| Total Shareholder Return Vs Peer Group [Text Block] | As demonstrated by the following graph, Comerica’s cumulative TSR over the three-year period presented in the table was 7%, while the cumulative TSR of Comerica's peer group presented for this purpose, the KBW Bank Index, was (3)% over the same three-year period. Comerica’s cumulative TSR outperformed the KBW Index during 2021 and 2022. For more information regarding the Comerica’s performance and the companies that the Committee considers when determining compensation, refer to “Compensation Discussion and Analysis.” | | |
| Tabular List [Table Text Block] | As described in greater detail in “Compensation Discussion and Analysis,” Comerica’s executive compensation program reflects a variable pay-for-performance philosophy. The metrics that the Company uses for both our long-term and short-term incentive awards are selected based on an objective of incentivizing our NEOs to increase the value of our enterprise for our shareholders . The most important financial performance measures used by Comerica to link executive compensation actually paid to Comerica’s NEOs, for the most recently completed fiscal year, to Comerica’s performance are as follows: • MIP EPS • MIP Efficiency Ratio • SELTPP ROCE • ROCE • Strategic Initiatives • Relative TSR (the Company’s TSR as compared to a peer group established by the Governance, Compensation and Nominating Committee) | | |
| Total Shareholder Return Amount | $ 107 | 134 | 83 |
| Peer Group Total Shareholder Return Amount | 97 | 124 | 89 |
| Net Income (Loss) | $ 1,151,000,000 | $ 1,168,000,000 | $ 497,000,000 |
| Company Selected Measure Amount | $ / shares | 6.83 | 6.12 | 5.14 |
| PEO Name | Mr. Farmer | | |
| Additional 402(v) Disclosure [Text Block] | The dollar amounts reported represent the amount of net income reflected in Comerica’s audited financial statements for the applicable year. | | |
| Measure [Axis]: 1 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | MIP EPS | | |
| Non-GAAP Measure Description [Text Block] | "MIP EPS" measures absolute performance for one-year earnings per share ("EPS") excluding non-performance items*, uses net-charge-offs in lieu of provision expense for credit losses, applies an interest rate collar of 50% and, for 2022, excludes the impact of any loss of hedge accounting treatment due to the LIBOR transition (all on a post-tax basis). "Non-performance items" include the after-tax impact of any adjustments related to a change in accounting principle, items that are deemed to be unusual/infrequently occurring, results from discontinued operations, merger/acquisition charges, changes in the corporate tax rate and restructuring charges incurred during the year, if applicable. Please see "Compensation Discussion and Analysis" for more information about this calculation. | | |
| Measure [Axis]: 2 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | MIP Efficiency Ratio | | |
| Non-GAAP Measure Description [Text Block] | "MIP Efficiency Ratio" measures absolute performance for one-year efficiency ratio excluding non-performance items* and applies an interest rate collar of 50% (all on a pre-tax basis). | | |
| Measure [Axis]: 3 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | SELTPP ROCE | | |
| Non-GAAP Measure Description [Text Block] | "SELTPP ROCE" measures Comerica's average return on common equity ("ROCE") excluding non-performance items* and utilizes net charge-offs instead of provision expense for credit losses. One-year computations are completed and averaged over the three-year performance period to determine SELTPP ROCE over a three-year period. | | |
| Measure [Axis]: 4 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | ROCE | | |
| Measure [Axis]: 5 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Strategic Initiatives | | |
| Measure [Axis]: 6 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Relative TSR (the Company’s TSR as compared to a peer group established by the Governance, Compensation and Nominating Committee) | | |
| Non-GAAP Measure Description [Text Block] | Total Shareholder Return ("TSR") is cumulative for the measurement periods beginning on December 31, 2019 and ending on the last fiscal day in 2022, 2021 and 2020, respectively, calculated in accordance with Item 201(e) of Regulation S-K. “Peer Group” represents the KBW Bank Index for each year disclosed in the table. | | |
| PEO [Member] | Adjustment, Equity Awards Reported Value [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | $ 4,281,205 | $ 3,805,582 | $ 3,188,716 |
| PEO [Member] | Adjustment, Equity Award Adjustments [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 3,162,544 | 7,734,030 | 149,175 |
| PEO [Member] | Adjustment, Reported Change In The Actuarial Present Value of Pension Benefits [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 187,153 | 114,858 | 158,455 |
| PEO [Member] | Adjustment, Pension Benefit [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 136,366 | 99,392 | 49,894 |
| PEO [Member] | Equity Awards Granted During the Year, Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 3,749,103 | 5,603,372 | 2,635,946 |
| PEO [Member] | Change in Fair Value of Equity Awards Outstanding and Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | (624,360) | 1,999,322 | (2,065,535) |
| PEO [Member] | Equity Awards Granted During the Year, Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 0 | 0 | 0 |
| PEO [Member] | Equity Awards Granted in Prior Years, Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 37,801 | 131,336 | (421,236) |
| PEO [Member] | Equity Awards that Failed to Meet Vesting Conditions [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 0 | 0 | 0 |
| PEO [Member] | Equity Awards, Value of Dividends and Other Earnings Paid Adjustment [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 0 | 0 | 0 |
| PEO [Member] | Pension Benefit, Service Cost Adjustment [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Pension Benefit | 136,366 | 95,950 | 49,894 |
| PEO [Member] | Pension Benefit, Prior Service Cost Adjustment [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Pension Benefit | 0 | 3,442 | 0 |
| Non-PEO NEO [Member] | Adjustment, Equity Awards Reported Value [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 899,126 | 911,371 | 799,843 |
| Non-PEO NEO [Member] | Adjustment, Equity Award Adjustments [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 18,834 | 1,800,780 | 841,834 |
| Non-PEO NEO [Member] | Adjustment, Reported Change In The Actuarial Present Value of Pension Benefits [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 23,937 | 27,476 | 130,925 |
| Non-PEO NEO [Member] | Adjustment, Pension Benefit [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 61,156 | 91,920 | 13,755 |
| Non-PEO NEO [Member] | Equity Awards Granted During the Year, Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 651,661 | 1,341,915 | 1,139,640 |
| Non-PEO NEO [Member] | Change in Fair Value of Equity Awards Outstanding and Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | (184,686) | 421,124 | (208,030) |
| Non-PEO NEO [Member] | Equity Awards Granted During the Year, Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 0 | 0 | 0 |
| Non-PEO NEO [Member] | Equity Awards Granted in Prior Years, Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 14,219 | 37,741 | (89,776) |
| Non-PEO NEO [Member] | Equity Awards that Failed to Meet Vesting Conditions [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | (462,360) | 0 | 0 |
| Non-PEO NEO [Member] | Equity Awards, Value of Dividends and Other Earnings Paid Adjustment [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Equity Awards | 0 | 0 | 0 |
| Non-PEO NEO [Member] | Pension Benefit, Service Cost Adjustment [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Pension Benefit | 61,156 | 51,737 | 13,755 |
| Non-PEO NEO [Member] | Pension Benefit, Prior Service Cost Adjustment [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount, Pension Benefit | $ 0 | $ 40,183 | $ 0 |
