Regulatory Ratios and Capital - Schedule of Compliance With Regulatory Capital Requirements (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	0.0600
Capital Required to be Well Capitalized to Risk Weighted Assets	0.1000
CET1, actual amount	$ 3,321,203	$ 3,251,979
Tier One Risk Based Capital	3,731,203	3,661,979
Capital	4,437,924	4,390,656
Tier One Leverage Capital	$ 3,731,203	$ 3,661,979
CET1, actual ratio	11.45%	11.38%
Tier One Risk Based Capital to Risk Weighted Assets	0.1286	0.1282
Capital to Risk Weighted Assets	0.1530	0.1537
Tier One Leverage Capital to Average Assets	0.1184	0.1133
Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
CET1 to be well capitalized under prompt corrective action provisions, ratio	6.50%
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	0.0800
Capital Required to be Well Capitalized to Risk Weighted Assets	0.1000
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	0.0500
CET1, actual amount	$ 3,397,976	$ 3,611,714
Tier One Risk Based Capital	3,397,976	3,611,714
Capital	3,732,255	3,968,168
Tier One Leverage Capital	$ 3,397,976	$ 3,611,714
CET1, actual ratio	11.81%	12.75%
Tier One Risk Based Capital to Risk Weighted Assets	0.1181	0.1275
Capital to Risk Weighted Assets	0.1297	0.1400
Tier One Leverage Capital to Average Assets	0.1087	0.1127
Basel III, Phase-In Schedule
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
CET1 for capital adequacy purposes, ratio	7.00%
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	0.0850
Capital Required for Capital Adequacy to Risk Weighted Assets	0.1050
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	0.0400
Basel III, Phase-In Schedule \| Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
CET1 for capital adequacy purposes, ratio	7.00%
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	0.0850
Capital Required for Capital Adequacy to Risk Weighted Assets	0.1050
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	0.0400

Common Equity Tier 1 Capital

No definition available.

Name:	tcbi_CommonEquityTier1Capital
Namespace Prefix:	tcbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Common Equity Tier 1, Capital Required for Capital Adequacy to Risk Weighted Assets

+ References

No definition available.

+ Details

Name:	tcbi_CommonEquityTier1CapitalRequiredforCapitalAdequacytoRiskWeightedAssets
Namespace Prefix:	tcbi_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Common Equity Tier 1, Capital Required to be Well Capitalized to Risk Weighted Assets

+ References

No definition available.

+ Details

Name:	tcbi_CommonEquityTier1CapitalRequiredtobeWellCapitalizedtoRiskWeightedAssets
Namespace Prefix:	tcbi_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Common Equity Tier 1, Capital to Risk Weighted Assets

+ References

No definition available.

+ Details

Name:	tcbi_CommonEquityTier1CapitaltoRiskWeightedAssets
Namespace Prefix:	tcbi_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of total capital as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_Capital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Ratio of minimum total risk-based capital to risk-weighted assets required for capital adequacy as defined by regulatory framework.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477270/942-505-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477270/942-505-50-1B

+ Details

Name:	us-gaap_CapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio of minimum total risk-based capital to risk-weighted assets categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio of total risk-based capital to risk-weighted assets as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_CapitalToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477270/942-505-50-1B

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477270/942-505-50-1

+ Details

Name:	us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of Tier 1 leverage capital as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Ratio of minimum Tier 1 leverage capital to average assets required for capital adequacy as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio of minimum Tier 1 leverage capital to average assets categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio of Tier 1 capital to average assets as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalToAverageAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of Tier 1 risk-based capital as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Ratio of minimum Tier 1 risk-based capital to risk-weighted assets required for capital adequacy as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio of minimum Tier 1 risk-based capital to risk-weighted assets categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio of Tier 1 risk-based capital to risk-weighted assets as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	srt_ConsolidatedEntitiesAxis=srt_SubsidiariesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RiskWeightedAssetsCalculationMethodologyAxis=tcbi_AdvancedApproachPhaseInScheduleMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: