Shareholders Equity and Regulatory Matters - Schedule of comparison of the actual capital amounts and ratios (Details) $ in Thousands	Mar. 31, 2026 USD ($)	Dec. 31, 2025 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total capital (to risk weighted assets), Actual, Amount	$ 715,701	$ 628,120
Total capital (to risk weighted assets), Actual, Ratio	0.1213	0.1248
Total capital (to risk weighted assets), For Capital Adequacy Purposes, Amount	$ 619,721	$ 528,317
Total capital (to risk weighted assets), For Capital Adequacy Purposes, Ratio	0.105	0.105
Tier 1 capital (to risk weighted assets), Actual, Amount	$ 587,977	$ 501,426
Tier 1 capital (to risk weighted assets), Actual, Ratio	0.0996	0.0997
Tier 1 capital (to risk weighted assets), For Capital Adequacy Purposes, Amount	$ 501,679	$ 427,686
Tier 1 capital (to risk weighted assets), For Capital Adequacy Purposes, Ratio	0.085	0.085
Tier 1 capital (to average assets), Actual, Amount	$ 587,977	$ 501,426
Tier 1 capital (to average assets), Actual, Ratio	0.0965	0.0965
Tier 1 capital (to average assets), For Capital Adequacy Purposes, Amount	$ 243,761	$ 207,886
Tier 1 capital (to average assets), For Capital Adequacy Purposes, Ratio	0.04	0.04
Common equity tier 1 (to risk weighted assets), Actual, Amount	$ 521,817	$ 435,266
Common equity tier 1 (to risk weighted assets), Actual, Ratio	0.0884	0.0865
Common equity tier 1 (to risk weighted assets), For Capital Adequacy Purposes, Amount	$ 413,147	$ 352,212
Common equity tier 1 (to risk weighted assets), For Capital Adequacy Purposes, Ratio	0.07	0.07
THIRD COAST BANK
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total capital (to risk weighted assets), Actual, Amount	$ 767,508	$ 660,607
Total capital (to risk weighted assets), Actual, Ratio	0.1302	0.1314
Total capital (to risk weighted assets), For Capital Adequacy Purposes, Amount	$ 618,878	$ 527,767
Total capital (to risk weighted assets), For Capital Adequacy Purposes, Ratio	0.105	0.105
Total capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 589,408	$ 502,636
Total capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	0.10	0.10
Tier 1 capital (to risk weighted assets), Actual, Amount	$ 720,800	$ 614,878
Tier 1 capital (to risk weighted assets), Actual, Ratio	0.1223	0.1223
Tier 1 capital (to risk weighted assets), For Capital Adequacy Purposes, Amount	$ 500,996	$ 427,240
Tier 1 capital (to risk weighted assets), For Capital Adequacy Purposes, Ratio	0.085	0.085
Tier 1 capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 471,526	$ 402,108
Tier 1 capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	0.08	0.08
Tier 1 capital (to average assets), Actual, Amount	$ 720,800	$ 614,878
Tier 1 capital (to average assets), Actual, Ratio	0.1184	0.1184
Tier 1 capital (to average assets), For Capital Adequacy Purposes, Amount	$ 243,552	$ 207,672
Tier 1 capital (to average assets), For Capital Adequacy Purposes, Ratio	0.04	0.04
Tier 1 capital (to average assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 304,440	$ 259,591
Tier 1 capital (to average assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	0.05	0.05
Common equity tier 1 (to risk weighted assets), Actual, Amount	$ 720,800	$ 614,878
Common equity tier 1 (to risk weighted assets), Actual, Ratio	0.1223	0.1223
Common equity tier 1 (to risk weighted assets), For Capital Adequacy Purposes, Amount	$ 412,585	$ 351,845
Common equity tier 1 (to risk weighted assets), For Capital Adequacy Purposes, Ratio	0.07	0.07
Common equity tier 1 (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 383,115	$ 326,713
Common equity tier 1 (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	0.065	0.065

Tier one risk based capital required for capital adequacy with buffer.

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

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
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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.

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