Shareholders Equity and Regulatory Matters - Schedule of comparison of the actual capital amounts and ratios (Details) $ in Thousands	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total capital (to risk weighted assets), Actual, Amount	$ 486,350
Total capital (to risk weighted assets), Actual, Ratio	0.126
Total capital (to risk weighted assets), For Capital Adequacy Purposes, Amount	$ 404,431
Total capital (to risk weighted assets), For Capital Adequacy Purposes, Ratio	0.105
Tier I capital (to risk weighted assets), Actual, Amount	$ 370,036
Tier I capital (to risk weighted assets), Actual, Ratio	0.096
Tier I capital (to risk weighted assets), For Capital Adequacy Purposes, Amount	$ 327,396
Tier I capital (to risk weighted assets), For Capital Adequacy Purposes, Ratio	0.085
Tier I capital (to average assets), Actual, Amount	$ 370,036
Tier I capital (to average assets), Actual, Ratio	0.101
Tier I capital (to average assets), For Capital Adequacy Purposes, Amount	$ 146,022
Tier I capital (to average assets), For Capital Adequacy Purposes, Ratio	0.040
Common equity tier 1 (to risk weighted assets), Actual, Amount	$ 303,811
Common equity tier 1 (to risk weighted assets), Actual, Ratio	0.079
Common equity tier 1 (to risk weighted assets), For Capital Adequacy Purposes, Amount	$ 269,620
Common equity tier 1 (to risk weighted assets), For Capital Adequacy Purposes, Ratio	0.070
THIRD COAST BANK, SSB
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total capital (to risk weighted assets), Actual, Amount	$ 509,870	$ 496,222
Total capital (to risk weighted assets), Actual, Ratio	0.133	0.138
Total capital (to risk weighted assets), For Capital Adequacy Purposes, Amount	$ 403,975	$ 377,782
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	$ 384,738	$ 359,793
Total capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	0.100	0.100
Tier I capital (to risk weighted assets), Actual, Amount	$ 473,954	$ 465,871
Tier I capital (to risk weighted assets), Actual, Ratio	0.123	0.129
Tier I capital (to risk weighted assets), For Capital Adequacy Purposes, Amount	$ 327,027	$ 305,824
Tier I capital (to risk weighted assets), For Capital Adequacy Purposes, Ratio	0.085	0.085
Tier I capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 307,790	$ 287,834
Tier I capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	0.080	0.080
Tier I capital (to average assets), Actual, Amount	$ 473,954	$ 465,871
Tier I capital (to average assets), Actual, Ratio	0.130	0.131
Tier I capital (to average assets), For Capital Adequacy Purposes, Amount	$ 145,862	$ 142,188
Tier I capital (to average assets), For Capital Adequacy Purposes, Ratio	0.040	0.040
Tier I capital (to average assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 182,328	$ 177,734
Tier I capital (to average assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	0.050	0.050
Common equity tier 1 (to risk weighted assets), Actual, Amount	$ 473,954	$ 465,871
Common equity tier 1 (to risk weighted assets), Actual, Ratio	0.123	0.129
Common equity tier 1 (to risk weighted assets), For Capital Adequacy Purposes, Amount	$ 269,317	$ 251,855
Common equity tier 1 (to risk weighted assets), For Capital Adequacy Purposes, Ratio	0.070	0.070
Common equity tier 1 (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 250,080	$ 233,865
Common equity tier 1 (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	0.065	0.065