Cover Page - shares	9 Months Ended
	Sep. 30, 2023	Oct. 31, 2023
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
Document Transition Report	false
Entity File Number	001-35077
Entity Registrant Name	WINTRUST FINANCIAL CORP
Entity Incorporation, State or Country Code	IL
Entity Tax Identification Number	36-3873352
Entity Address, Address Line One	9700 W. Higgins Road, Suite 800
Entity Address, City or Town	Rosemont
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60018
City Area Code	847
Local Phone Number	939-9000
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 (in shares)		61,236,454
Entity Central Index Key	0001015328
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false
Common Stock, no par value
Entity Information [Line Items]
Title of 12(b) Security	Common Stock, no par value
Trading Symbol	WTFC
Security Exchange Name	NASDAQ
Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series D, no par value
Entity Information [Line Items]
Title of 12(b) Security	Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series D, no par value
Trading Symbol	WTFCM
Security Exchange Name	NASDAQ
6.875% Fixed-Rate Reset Non-Cumulative Perpetual Preferred Stock, Series E, no par value
Entity Information [Line Items]
Title of 12(b) Security	6.875% Fixed-Rate Reset Non-Cumulative Perpetual Preferred Stock, Series E, no par value
Trading Symbol	WTFCP
Security Exchange Name	NASDAQ