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Junior Subordinated Debentures - Schedule of Junior Subordinated Debentures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Subordinated Borrowing [Line Items]
Junior subordinated debentures	$ 253,566	$ 253,566
Junior Subordinated Debt
Subordinated Borrowing [Line Items]
Junior subordinated debentures	$ 253,566	253,566
Contractual rate (as a percent)	6.19%
Junior Subordinated Debt | Wintrust Capital Trust III
Subordinated Borrowing [Line Items]
Common Securities	$ 774
Trust Preferred Securities	25,000
Junior subordinated debentures	$ 25,774	25,774
Rate Structure, stated	0.26161%
Rate Structure, variable	3.25%
Contractual rate (as a percent)	7.42%
Junior Subordinated Debt | Wintrust Statutory Trust IV
Subordinated Borrowing [Line Items]
Common Securities	$ 619
Trust Preferred Securities	20,000
Junior subordinated debentures	$ 20,619	20,619
Rate Structure, stated	0.26161%
Rate Structure, variable	2.80%
Contractual rate (as a percent)	6.73%
Junior Subordinated Debt | Wintrust Statutory Trust V
Subordinated Borrowing [Line Items]
Common Securities	$ 1,238
Trust Preferred Securities	40,000
Junior subordinated debentures	$ 41,238	41,238
Rate Structure, stated	0.26161%
Rate Structure, variable	2.60%
Contractual rate (as a percent)	6.53%
Junior Subordinated Debt | Wintrust Capital Trust VII
Subordinated Borrowing [Line Items]
Common Securities	$ 1,550
Trust Preferred Securities	50,000
Junior subordinated debentures	$ 51,550	51,550
Rate Structure, stated	0.26161%
Rate Structure, variable	1.95%
Contractual rate (as a percent)	5.93%
Junior Subordinated Debt | Wintrust Capital Trust VIII
Subordinated Borrowing [Line Items]
Common Securities	$ 1,238
Trust Preferred Securities	25,000
Junior subordinated debentures	$ 26,238	26,238
Rate Structure, stated	0.26161%
Rate Structure, variable	1.45%
Contractual rate (as a percent)	5.38%
Junior Subordinated Debt | Wintrust Capital Trust IX
Subordinated Borrowing [Line Items]
Common Securities	$ 1,547
Trust Preferred Securities	50,000
Junior subordinated debentures	$ 51,547	51,547
Rate Structure, stated	0.26161%
Rate Structure, variable	1.63%
Contractual rate (as a percent)	5.61%
Junior Subordinated Debt | Northview Capital Trust I
Subordinated Borrowing [Line Items]
Common Securities	$ 186
Trust Preferred Securities	6,000
Junior subordinated debentures	$ 6,186	6,186
Rate Structure, stated	0.26161%
Rate Structure, variable	3.00%
Contractual rate (as a percent)	7.12%
Junior Subordinated Debt | Town Bankshares Capital Trust I
Subordinated Borrowing [Line Items]
Common Securities	$ 186
Trust Preferred Securities	6,000
Junior subordinated debentures	$ 6,186	6,186
Rate Structure, stated	0.26161%
Rate Structure, variable	3.00%
Contractual rate (as a percent)	7.12%
Junior Subordinated Debt | First Northwest Capital Trust I
Subordinated Borrowing [Line Items]
Common Securities	$ 155
Trust Preferred Securities	5,000
Junior subordinated debentures	$ 5,155	5,155
Rate Structure, stated	0.26161%
Rate Structure, variable	3.00%
Contractual rate (as a percent)	6.93%
Junior Subordinated Debt | Suburban Illinois Capital Trust II
Subordinated Borrowing [Line Items]
Common Securities	$ 464
Trust Preferred Securities	15,000
Junior subordinated debentures	$ 15,464	15,464
Rate Structure, stated	0.26161%
Rate Structure, variable	1.75%
Contractual rate (as a percent)	5.73%
Junior Subordinated Debt | Community Financial Shares Statutory Trust II
Subordinated Borrowing [Line Items]
Common Securities	$ 109
Trust Preferred Securities	3,500
Junior subordinated debentures	$ 3,609	$ 3,609
Rate Structure, stated	0.26161%
Rate Structure, variable	1.62%
Contractual rate (as a percent)	5.60%

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