Cover - shares	3 Months Ended
	Mar. 31, 2023	Apr. 26, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2023
Document Transition Report	false
Entity File Number	1-10706
Entity Registrant Name	Comerica Incorporated
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	38-1998421
Entity Address, Address Line One	1717 Main Street, MC 6500
Entity Address, City or Town	Dallas
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	75201
City Area Code	(214)
Local Phone Number	462-6831
Title of 12(b) Security	Common Stock, $5 par value
Trading Symbol	CMA
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		131,669,861
Entity Central Index Key	0000028412
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q1
Amendment Flag	false