Business Combinations	9 Months Ended
Sep. 30, 2022
Business Combination and Asset Acquisition [Abstract]
Business Combinations	Business CombinationsOn November 15, 2021, the Company completed its acquisition of certain assets from The Allstate Corporation (“Allstate”). Through this business combination, the Company acquired approximately $581.6 million of loans, net of allowance for credit losses measured on the acquisition date. The loan portfolio was comprised of approximately 1,800 loans to Allstate agents nationally. In addition to acquiring the loans, the Company became the national preferred provider of loans to Allstate agents. In connection with the loan acquisition, a team of Allstate agency lending specialists joined the Company to augment and expand Wintrust’s existing insurance agency finance business. For more information regarding these loans, see Note 6 - Loans in Item 1 of this report. As the transaction was determined to be a business combination, the Company recorded goodwill of approximately $9.3 million on the acquisition.

The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-URI https://asc.fasb.org/topic&trid=2303972

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=128092470&loc=d3e4946-128472

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