No definition available.

Name:	tcbi_FairValueAssetsMeasuredOnNonRecurringBasisUnobservableInputReconciliationLineItems
Namespace Prefix:	tcbi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair Value Measurement With Unobservable Inputs Reconciliation Non Recurring Basis Asset Gain Loss Included In Earnings

+ References

No definition available.

+ Details

Name:	tcbi_FairValueMeasurementWithUnobservableInputsReconciliationNonRecurringBasisAssetGainLossIncludedInEarnings
Namespace Prefix:	tcbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Fair Value Measurement With Unobservable Inputs Reconciliation Non Recurring Basis Asset Value

+ References

No definition available.

+ Details

Name:	tcbi_FairValueMeasurementWithUnobservableInputsReconciliationNonRecurringBasisAssetValue
Namespace Prefix:	tcbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Value of input used to measure 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/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 103
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-103

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleMeasurementInput
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Period between issuance and maturity of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482907/825-10-50-10

+ Details

Name:	us-gaap_LoansReceivableFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsNonrecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_CreditRiskContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputDiscountRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_WeightedAverageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Fair Value Disclosures - Narrative (Details) $ in Millions	3 Months Ended
Fair Value Disclosures - Narrative (Details) $ in Millions	Jun. 30, 2024 USD ($)	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Fair Value, Inputs, Level 3 \| Fair Value, Measurements, Nonrecurring
Fair Value Assets Measured On Non Recurring Basis Unobservable Input Reconciliation [Line Items]
Loans held for investment, net	$ 18.0		$ 38.3
Impaired loans, carrying value	42.8		$ 58.3
Allowance allocations	$ 24.8	$ 20.0
CRT securities \| Minimum
Fair Value Assets Measured On Non Recurring Basis Unobservable Input Reconciliation [Line Items]
Debt securities, available-for-sale, term	4 years 7 months 17 days
CRT securities \| Maximum
Fair Value Assets Measured On Non Recurring Basis Unobservable Input Reconciliation [Line Items]
Debt securities, available-for-sale, term	7 years 2 months 1 day
Measurement Input, Discount Rate \| CRT securities \| Minimum
Fair Value Assets Measured On Non Recurring Basis Unobservable Input Reconciliation [Line Items]
Debt securities, available-for-sale, measurement input	0.0515
Measurement Input, Discount Rate \| CRT securities \| Maximum
Fair Value Assets Measured On Non Recurring Basis Unobservable Input Reconciliation [Line Items]
Debt securities, available-for-sale, measurement input	0.0699
Measurement Input, Discount Rate \| CRT securities \| Weighted Average
Fair Value Assets Measured On Non Recurring Basis Unobservable Input Reconciliation [Line Items]
Debt securities, available-for-sale, measurement input	0.0583		0.0657
Debt securities, available-for-sale, term	5 years 6 months 25 days		6 years 21 days