The total amount of cash and securities held by third party trustees pursuant to terms of debt instruments or other agreements as of the date of each statement of financial position presented, which can be used by the trustee only to pay the noncurrent portion of specified obligations.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Face (par) amount of debt instrument at time of issuance.

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Including the current and noncurrent portions, the carrying value of junior subordinated long-term debt owed to unconsolidated subsidiary trusts as of the balance sheet date. Such debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets and was initially scheduled to be repaid after one year or beyond the normal operating cycle if longer.

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Junior Subordinated Debentures - Schedule of Junior Subordinated Debentures (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Subordinated Borrowing [Line Items]
Junior subordinated debentures	$ 253,566	$ 253,566	$ 253,566
Junior Subordinated Debt
Subordinated Borrowing [Line Items]
Junior subordinated debentures	$ 253,566	$ 253,600	$ 253,600
Contractual rate	7.85%
Junior Subordinated Debt \| Wintrust Capital Trust III
Subordinated Borrowing [Line Items]
Common Securities	$ 774
Trust Preferred Securities	25,000
Junior subordinated debentures	$ 25,774
Rate structure, stated	0.26161%
Contractual rate	8.82%
Junior Subordinated Debt \| Wintrust Capital Trust III \| Secured Overnight Financing Rate (SOFR)
Subordinated Borrowing [Line Items]
Rate structure, variable	3.25%
Junior Subordinated Debt \| Wintrust Statutory Trust IV
Subordinated Borrowing [Line Items]
Common Securities	$ 619
Trust Preferred Securities	20,000
Junior subordinated debentures	$ 20,619
Rate structure, stated	0.26161%
Contractual rate	8.46%
Junior Subordinated Debt \| Wintrust Statutory Trust IV \| Secured Overnight Financing Rate (SOFR)
Subordinated Borrowing [Line Items]
Rate structure, variable	2.80%
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
Rate structure, stated	0.26161%
Contractual rate	8.26%
Junior Subordinated Debt \| Wintrust Statutory Trust V \| Secured Overnight Financing Rate (SOFR)
Subordinated Borrowing [Line Items]
Rate structure, variable	2.60%
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
Rate structure, stated	0.26161%
Contractual rate	7.62%
Junior Subordinated Debt \| Wintrust Capital Trust VII \| Secured Overnight Financing Rate (SOFR)
Subordinated Borrowing [Line Items]
Rate structure, variable	1.95%
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
Rate structure, stated	0.26161%
Contractual rate	7.11%
Junior Subordinated Debt \| Wintrust Capital Trust VIII \| Secured Overnight Financing Rate (SOFR)
Subordinated Borrowing [Line Items]
Rate structure, variable	1.45%
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
Rate structure, stated	0.26161%
Contractual rate	7.30%
Junior Subordinated Debt \| Wintrust Capital Trust IX \| Secured Overnight Financing Rate (SOFR)
Subordinated Borrowing [Line Items]
Rate structure, variable	1.63%
Junior Subordinated Debt \| Northview Capital Trust I
Subordinated Borrowing [Line Items]
Common Securities	$ 186
Trust Preferred Securities	6,000
Junior subordinated debentures	$ 6,186
Rate structure, stated	0.26161%
Contractual rate	8.63%
Junior Subordinated Debt \| Northview Capital Trust I \| Secured Overnight Financing Rate (SOFR)
Subordinated Borrowing [Line Items]
Rate structure, variable	3.00%
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
Rate structure, stated	0.26161%
Contractual rate	8.63%
Junior Subordinated Debt \| Town Bankshares Capital Trust I \| Secured Overnight Financing Rate (SOFR)
Subordinated Borrowing [Line Items]
Rate structure, variable	3.00%
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
Rate structure, stated	0.26161%
Contractual rate	8.66%
Junior Subordinated Debt \| First Northwest Capital Trust I \| Secured Overnight Financing Rate (SOFR)
Subordinated Borrowing [Line Items]
Rate structure, variable	3.00%
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
Rate structure, stated	0.26161%
Contractual rate	7.42%
Junior Subordinated Debt \| Suburban Illinois Capital Trust II \| Secured Overnight Financing Rate (SOFR)
Subordinated Borrowing [Line Items]
Rate structure, variable	1.75%
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
Rate structure, stated	0.26161%
Contractual rate	7.29%
Junior Subordinated Debt \| Community Financial Shares Statutory Trust II \| Secured Overnight Financing Rate (SOFR)
Subordinated Borrowing [Line Items]
Rate structure, variable	1.62%