| Document And Entity Information Document | Oct. 20, 2020 |
| Entity Information [Line Items] | |
| Entity Registrant Name | TEXAS CAPITAL BANCSHARES INC/TX |
| Entity Emerging Growth Company | false |
| Entity Incorporation, State or Country Code | DE |
| Written Communications | false |
| Document Type | 8-K |
| Document Period End Date | Oct. 20, 2020 |
| Entity Address, Address Line One | 2000 McKinney Avenue |
| Entity Address, Address Line Two | Suite 700 |
| Entity Address, City or Town | Dallas |
| Entity Address, State or Province | TX |
| Entity Address, Postal Zip Code | 75201 |
| City Area Code | (214) |
| Local Phone Number | 932-6600 |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity File Number | 001-34657 |
| Entity Tax Identification Number | 75-2679109 |
| Entity Central Index Key | 0001077428 |
| Amendment Flag | false |
| Common Stock [Member] | |
| Entity Information [Line Items] | |
| Title of 12(b) Security | Common Stock, par value $0.01 per share |
| Trading Symbol | TCBI |
| Security Exchange Name | NASDAQ |
| Series A Preferred Stock [Member] | |
| Entity Information [Line Items] | |
| Title of 12(b) Security | 6.50% Non-Cumulative Perpetual Preferred Stock Series A, par value $0.01 per share |
| Trading Symbol | TCBIP |
| Security Exchange Name | NASDAQ |
