Junior Subordinated Debentures (Summary of the Company's Junior Subordinated Debentures) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
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
Average contractual rate	6.87%
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
Contractual rate	7.33%
Junior Subordinated Debt | Wintrust Capital Trust III | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure	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	20,619
Contractual rate	7.55%
Junior Subordinated Debt | Wintrust Statutory Trust IV | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure	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	41,238
Contractual rate	7.35%
Junior Subordinated Debt | Wintrust Statutory Trust V | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure	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	51,550
Contractual rate	6.72%
Junior Subordinated Debt | Wintrust Capital Trust VII | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure	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	26,238
Contractual rate	6.20%
Junior Subordinated Debt | Wintrust Capital Trust VIII | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure	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	51,547
Contractual rate	6.40%
Junior Subordinated Debt | Wintrust Capital Trust IX | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure	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	6,186
Contractual rate	7.44%
Junior Subordinated Debt | Northview Capital Trust I | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure	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	6,186
Contractual rate	7.44%
Junior Subordinated Debt | Town Bankshares Capital Trust I | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure	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	5,155
Contractual rate	7.75%
Junior Subordinated Debt | First Northwest Capital Trust I | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure	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	15,464
Contractual rate	6.52%
Junior Subordinated Debt | Suburban Illinois Capital Trust II | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure	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	$ 3,609
Contractual rate	6.39%
Junior Subordinated Debt | Community Financial Shares Statutory Trust II | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate Structure	1.62%