Junior Subordinated Debentures (Summary of the Company's Junior Subordinated Debentures) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014 Rate	Dec. 31, 2013
Subordinated Borrowing [Line Items]
Junior subordinated debentures	$ 249,493	$ 249,493
Wintrust Capital Trust Three [Member]
Subordinated Borrowing [Line Items]
Assets Held-in-trust	774
Trust preferred securities	25,000
Junior subordinated debentures	25,774	25,774
Debt Instrument, Interest Rate Terms	L+3.25
Debt Instrument, Interest Rate, Stated Percentage	3.48%
Issue date	Apr. 30, 2003
Maturity date	Apr. 30, 2033
Debt Instrument, Redemption Period, Start Date	Apr. 30, 2008
Wintrust Statutory Trust Four [Member]
Subordinated Borrowing [Line Items]
Assets Held-in-trust	619
Trust preferred securities	20,000
Junior subordinated debentures	20,619	20,619
Debt Instrument, Interest Rate Terms	L+2.80
Debt Instrument, Interest Rate, Stated Percentage	3.06%
Issue date	Dec. 31, 2003
Maturity date	Dec. 31, 2033
Debt Instrument, Redemption Period, Start Date	Dec. 31, 2008
Wintrust Statutory Trust Five [Member]
Subordinated Borrowing [Line Items]
Assets Held-in-trust	1,238
Trust preferred securities	40,000
Junior subordinated debentures	41,238	41,238
Debt Instrument, Interest Rate Terms	L+2.60
Debt Instrument, Interest Rate, Stated Percentage	2.86%
Issue date	May 31, 2004
Maturity date	May 31, 2034
Debt Instrument, Redemption Period, Start Date	Jun. 30, 2009
Wintrust Capital Trust Seven [Member]
Subordinated Borrowing [Line Items]
Assets Held-in-trust	1,550
Trust preferred securities	50,000
Junior subordinated debentures	51,550	51,550
Debt Instrument, Interest Rate Terms	L+1.95
Debt Instrument, Interest Rate, Stated Percentage	2.19%
Issue date	Dec. 31, 2004
Maturity date	Mar. 31, 2035
Debt Instrument, Redemption Period, Start Date	Mar. 31, 2010
Wintrust Capital Trust Eight [Member]
Subordinated Borrowing [Line Items]
Assets Held-in-trust	1,238
Trust preferred securities	40,000
Junior subordinated debentures	41,238	41,238
Debt Instrument, Interest Rate Terms	L+1.45
Debt Instrument, Interest Rate, Stated Percentage	1.71%
Issue date	Aug. 31, 2005
Maturity date	Sep. 30, 2035
Debt Instrument, Redemption Period, Start Date	Sep. 30, 2010
Wintrust Captial Trust Nine [Member]
Subordinated Borrowing [Line Items]
Assets Held-in-trust	1,547
Trust preferred securities	50,000
Junior subordinated debentures	51,547	51,547
Debt Instrument, Interest Rate Terms	L+1.63
Debt Instrument, Interest Rate, Stated Percentage	1.87%
Issue date	Sep. 30, 2006
Maturity date	Sep. 30, 2036
Debt Instrument, Redemption Period, Start Date	Sep. 30, 2011
Northview Capital Trust One [Member]
Subordinated Borrowing [Line Items]
Assets Held-in-trust	186
Trust preferred securities	6,000
Junior subordinated debentures	6,186	6,186
Debt Instrument, Interest Rate Terms	L+3.00
Debt Instrument, Interest Rate, Stated Percentage	3.24%
Issue date	Aug. 31, 2003
Maturity date	Nov. 30, 2033
Debt Instrument, Redemption Period, Start Date	Aug. 31, 2008
Town Bankshares Capital Trust One [Member]
Subordinated Borrowing [Line Items]
Assets Held-in-trust	186
Trust preferred securities	6,000
Junior subordinated debentures	6,186	6,186
Debt Instrument, Interest Rate Terms	L+3.00
Debt Instrument, Interest Rate, Stated Percentage	3.24%
Issue date	Aug. 31, 2003
Maturity date	Nov. 30, 2033
Debt Instrument, Redemption Period, Start Date	Aug. 31, 2008
First Northwest Capital Trust One [Member]
Subordinated Borrowing [Line Items]
Assets Held-in-trust	155
Trust preferred securities	5,000
Junior subordinated debentures	$ 5,155	$ 5,155
Debt Instrument, Interest Rate Terms	L+3.00
Debt Instrument, Interest Rate, Stated Percentage	3.26%
Issue date	May 31, 2004
Maturity date	May 31, 2034
Debt Instrument, Redemption Period, Start Date	May 31, 2009
Junior Subordinated Debt [Member]
Subordinated Borrowing [Line Items]
Weighted average interest rate	2.43%
London Interbank Offered Rate (LIBOR) [Member] \| Wintrust Capital Trust Three [Member]
Subordinated Borrowing [Line Items]
Debt Instrument, Basis Spread on Variable Rate	3.25%
London Interbank Offered Rate (LIBOR) [Member] \| Wintrust Statutory Trust Four [Member]
Subordinated Borrowing [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.80%
London Interbank Offered Rate (LIBOR) [Member] \| Wintrust Statutory Trust Five [Member]
Subordinated Borrowing [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.60%
London Interbank Offered Rate (LIBOR) [Member] \| Wintrust Capital Trust Seven [Member]
Subordinated Borrowing [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.95%
London Interbank Offered Rate (LIBOR) [Member] \| Wintrust Capital Trust Eight [Member]
Subordinated Borrowing [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.45%
London Interbank Offered Rate (LIBOR) [Member] \| Wintrust Captial Trust Nine [Member]
Subordinated Borrowing [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.63%
London Interbank Offered Rate (LIBOR) [Member] \| Northview Capital Trust One [Member]
Subordinated Borrowing [Line Items]
Debt Instrument, Basis Spread on Variable Rate	3.00%
London Interbank Offered Rate (LIBOR) [Member] \| Town Bankshares Capital Trust One [Member]
Subordinated Borrowing [Line Items]
Debt Instrument, Basis Spread on Variable Rate	3.00%
London Interbank Offered Rate (LIBOR) [Member] \| First Northwest Capital Trust One [Member]
Subordinated Borrowing [Line Items]
Debt Instrument, Basis Spread on Variable Rate	3.00%

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.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Face (par) amount of debt instrument at time of issuance.

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

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-Publisher SEC

-Name Regulation S-X (SX)

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Description of the interest rate as being fixed or variable, and, if variable, identification of the index or rate on which the interest rate is based and the number of points or percentage added to that index or rate to set the rate, and other pertinent information, such as frequency of rate resets.

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- Definition

Date the debt instrument was issued, in CCYY-MM-DD format.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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Start date of debt instrument redemption period, in CCYY-MM-DD format.

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- Definition

Weighted average interest rate of debt outstanding.

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No definition available.

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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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