XML 53 R43.htm IDEA: XBRL DOCUMENT
v3.25.2

Investment Securities - Schedule of Investment Securities (Details) - USD ($) | Jun. 30, 2025 | Dec. 31, 2024 | Jun. 30, 2024
--- | --- | --- | ---
Available-for-sale securities |  |  |
Amortized Cost | $ 5,389,193,000 | $ 4,725,539,000 | $ 4,906,690,000
Gross Unrealized Gains | 7,097,000 | 2,071,000 | 1,393,000
Gross Unrealized Losses | (510,575,000) | (586,128,000) | (578,126,000)
Fair Value | 4,885,715,000 | 4,141,482,000 | 4,329,957,000
Held-to-maturity securities |  |  |
Amortized Cost | 3,502,584,000 | 3,613,720,000 | 3,756,415,000
Gross Unrealized Gains | 3,041,000 | 1,066,000 | 517,000
Gross Unrealized Losses | (636,210,000) | (704,236,000) | (696,465,000)
Fair Value | 2,869,415,000 | 2,910,550,000 | 3,060,467,000
Less: Allowance for credit losses | (398,000) | (457,000) | (491,000)
Held-to-maturity securities, net of allowance for credit losses | 3,502,186,000 | 3,613,263,000 | 3,755,924,000
Equity securities with readily determinable fair value |  |  |
Amortized Cost | 273,789,000 | 220,758,000 | 117,674,000
Gross Unrealized Gains | 7,047,000 | 2,905,000 | 2,882,000
Gross Unrealized Losses | (7,114,000) | (8,251,000) | (8,383,000)
Fair Value | 273,722,000 | 215,412,000 | 112,173,000
U.S. Treasury |  |  |
Available-for-sale securities |  |  |
Amortized Cost | 12,979,000 | 37,858,000 | 102,721,000
Gross Unrealized Gains | 39,000 | 49,000 | 5,000
Gross Unrealized Losses | 0 | 0 | (14,000)
Fair Value | 13,018,000 | 37,907,000 | 102,712,000
U.S. government agencies |  |  |
Available-for-sale securities |  |  |
Amortized Cost | 50,000,000 | 50,000,000 | 50,000,000
Gross Unrealized Gains | 0 | 0 | 0
Gross Unrealized Losses | (4,176,000) | (5,055,000) | (4,808,000)
Fair Value | 45,824,000 | 44,945,000 | 45,192,000
Held-to-maturity securities |  |  |
Amortized Cost | 313,540,000 | 313,539,000 | 336,458,000
Gross Unrealized Gains | 0 | 0 | 0
Gross Unrealized Losses | (64,071,000) | (69,127,000) | (70,928,000)
Fair Value | 249,469,000 | 244,412,000 | 265,530,000
Municipal |  |  |
Available-for-sale securities |  |  |
Amortized Cost | 182,761,000 | 188,405,000 | 151,347,000
Gross Unrealized Gains | 1,120,000 | 528,000 | 390,000
Gross Unrealized Losses | (3,237,000) | (4,340,000) | (5,129,000)
Fair Value | 180,644,000 | 184,593,000 | 146,608,000
Held-to-maturity securities |  |  |
Amortized Cost | 156,753,000 | 161,016,000 | 166,400,000
Gross Unrealized Gains | 296,000 | 243,000 | 155,000
Gross Unrealized Losses | (4,030,000) | (5,290,000) | (6,789,000)
Fair Value | 153,019,000 | 155,969,000 | 159,766,000
Corporate notes |  |  |
Held-to-maturity securities |  |  |
Amortized Cost | 53,531,000 | 56,851,000 | 57,199,000
Gross Unrealized Gains | 75,000 | 8,000 | 0
Gross Unrealized Losses | (1,000,000) | (1,870,000) | (3,211,000)
Fair Value | 52,606,000 | 54,989,000 | 53,988,000
Financial issuers |  |  |
Available-for-sale securities |  |  |
Amortized Cost | 82,000,000 | 83,997,000 | 83,996,000
Gross Unrealized Gains | 0 | 0 | 0
Gross Unrealized Losses | (3,199,000) | (3,828,000) | (7,011,000)
Fair Value | 78,801,000 | 80,169,000 | 76,985,000
Other |  |  |
Available-for-sale securities |  |  |
Amortized Cost | 1,000,000 | 1,000,000 | 1,000,000
Gross Unrealized Gains | 0 | 0 | 0
Gross Unrealized Losses | (2,000) | (7,000) | (10,000)
Fair Value | 998,000 | 993,000 | 990,000
Residential mortgage-backed securities |  |  |
Available-for-sale securities |  |  |
Amortized Cost | 4,618,492,000 | 4,106,641,000 | 4,320,215,000
Gross Unrealized Gains | 3,960,000 | 284,000 | 361,000
Gross Unrealized Losses | (478,768,000) | (553,287,000) | (541,742,000)
Fair Value | 4,143,684,000 | 3,553,638,000 | 3,778,834,000
Held-to-maturity securities |  |  |
Amortized Cost | 2,775,981,000 | 2,864,927,000 | 2,962,721,000
Gross Unrealized Gains | 1,637,000 | 0 | 0
Gross Unrealized Losses | (548,063,000) | (605,014,000) | (591,601,000)
Fair Value | 2,229,555,000 | 2,259,913,000 | 2,371,120,000
Commercial (multi-family) mortgage-backed securities |  |  |
Available-for-sale securities |  |  |
Amortized Cost | 130,464,000 | 19,064,000 | 18,096,000
Gross Unrealized Gains | 115,000 | 23,000 | 8,000
Gross Unrealized Losses | (3,634,000) | (755,000) | (626,000)
Fair Value | 126,945,000 | 18,332,000 | 17,478,000
Held-to-maturity securities |  |  |
Amortized Cost | 6,333,000 | 6,364,000 | 6,390,000
Gross Unrealized Gains | 51,000 | 0 | 0
Gross Unrealized Losses | (113,000) | (252,000) | (300,000)
Fair Value | 6,271,000 | 6,112,000 | 6,090,000
Collateralized mortgage obligations |  |  |
Available-for-sale securities |  |  |
Amortized Cost | 311,497,000 | 238,574,000 | 179,315,000
Gross Unrealized Gains | 1,863,000 | 1,187,000 | 629,000
Gross Unrealized Losses | (17,559,000) | (18,856,000) | (18,786,000)
Fair Value | 295,801,000 | 220,905,000 | 161,158,000
Held-to-maturity securities |  |  |
Amortized Cost | 196,446,000 | 211,023,000 | 227,247,000
Gross Unrealized Gains | 982,000 | 815,000 | 362,000
Gross Unrealized Losses | (18,933,000) | (22,683,000) | (23,636,000)
Fair Value | 178,495,000 | 189,155,000 | 203,973,000
Mortgage-backed securities, subprime |  |  |
Available-for-sale securities |  |  |
Fair Value | $ 0 | $ 0 | $ 0

X
- Definition Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-2 + Details
Name: | us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-2 + Details
Name: | us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_AvailableForSaleSecuritiesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amortized cost excluding accrued interest, before allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479130/326-30-45-1 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479130/326-30-45-1 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount, excluding accrued interest, of allowance for credit loss on investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479344/326-20-45-1 + Details
Name: | us-gaap_DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount excluding accrued interest, after allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479344/326-20-45-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5 + Details
Name: | us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_EquitySecuritiesFVNIAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482736/825-10-45-1A Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(2)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483467/210-10-45-1 + Details
Name: | us-gaap_EquitySecuritiesFvNi
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Cost of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Excludes equity method investment and investment in equity security without readily determinable fair value. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(1)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 + Details
Name: | us-gaap_EquitySecuritiesFvNiCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount, before allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479344/326-20-45-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482736/825-10-45-1A Reference 3: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7A -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-7A Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 14 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-14 + Details
Name: | us-gaap_HeldToMaturitySecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_HeldToMaturitySecuritiesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5A -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5A + Details
Name: | us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5A -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5A + Details
Name: | us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 28 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482907/825-10-50-28 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 11 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482907/825-10-50-11 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 11 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482907/825-10-50-11 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2E -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2E Reference 6: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (aa) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(1)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5A -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5A Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 + Details
Name: | us-gaap_HeldToMaturitySecuritiesFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Equity Securities, FV-NI, Accumulated Unrealized Gain + References No definition available. + Details
Name: | wtfc_EquitySecuritiesFVNIAccumulatedUnrealizedGain
Namespace Prefix: | wtfc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Equity Securities, FV-NI, Accumulated Unrealized Loss + References No definition available. + Details
Name: | wtfc_EquitySecuritiesFVNIAccumulatedUnrealizedLoss
Namespace Prefix: | wtfc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USTreasurySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_MunicipalBondsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_CorporateAndOtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=wtfc_CorporateFinancialDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=wtfc_CorporateOtherDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_ResidentialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_CommercialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_CollateralizedMortgageObligationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=wtfc_MortgageBackedSecuritiesSubprimeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |