Loans and Allowance for Credit Losses on Loans - Age Analysis (Details) - USD ($)	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	$ 24,293,675,000		$ 22,542,823,000
Non-accrual	96,084,000
Non-accrual With No Allowance	7,641,000
Non-accrual loans earning interest income on cash basis	556,000		360,000
Interest income on non-accrual loans	630,000	$ 272,000
Interest Income Reversed	1,500,000	$ 917,000
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	11,999,025,000		11,145,591,000
Non-accrual	71,966,000
Non-accrual With No Allowance	3,073,000
Mortgage finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	6,057,804,000		5,215,574,000
Non-accrual	0
Non-accrual With No Allowance	0
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	5,696,720,000		5,616,282,000
Non-accrual	24,118,000
Non-accrual With No Allowance	4,568,000
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	540,126,000		$ 565,376,000
Non-accrual	0
Non-accrual With No Allowance	0
30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	5,498,000
30-59 Days Past Due \| Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	5,202,000
30-59 Days Past Due \| Mortgage finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0
30-59 Days Past Due \| Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	296,000
30-59 Days Past Due \| Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0
60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	3,436,000
60-89 Days Past Due \| Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	1,340,000
60-89 Days Past Due \| Mortgage finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0
60-89 Days Past Due \| Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	2,096,000
60-89 Days Past Due \| Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0
90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	126,000
90 Days or More Past Due \| Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	126,000
90 Days or More Past Due \| Mortgage finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0
90 Days or More Past Due \| Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0
90 Days or More Past Due \| Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0
Total Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	9,060,000
Total Past Due \| Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	6,668,000
Total Past Due \| Mortgage finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0
Total Past Due \| Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	2,392,000
Total Past Due \| Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0
Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	24,188,531,000
Current \| Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	11,920,391,000
Current \| Mortgage finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	6,057,804,000
Current \| Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	5,670,210,000
Current \| Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	$ 540,126,000

TEXAS CAPITAL BANCSHARES INC/TX 10-Q