Parent Company Only (Details 1) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Earnings
Interest on loans									$ 1,284,036	$ 1,124,970	$ 846,292
Other non-interest income									45,005	26,559	15,080
Interest expense	$ 89,372	$ 102,933	$ 103,340	$ 89,947	$ 81,045	$ 69,579	$ 55,140	$ 43,569	385,592	249,333	117,971
Salaries and employee benefits									315,080	291,768	264,231
Legal and professional									53,830	42,990	29,731
Other non-interest expense									47,246	50,890	42,859
Income tax expense	16,539	23,958	21,387	22,411	19,200	22,998	18,424	19,342	84,295	79,964	128,645
Net income	73,917	88,141	77,969	82,839	71,891	85,552	71,436	71,945	322,866	300,824	197,063
Preferred stock dividends	2,437	2,438	2,437	2,438	2,437	2,438	2,437	2,438	9,750	9,750	9,750
Net income available to common stockholders	$ 71,480	$ 85,703	$ 75,532	$ 80,401	$ 69,454	$ 83,114	$ 68,999	$ 69,507	313,116	291,074	187,313
Texas Capital Bancshares, Inc.
Statement of Earnings
Interest on loans									3,401	3,398	3,271
Dividend income									10,400	10,400	10,400
Other income									151	142	108
Total income									13,952	13,940	13,779
Other non-interest income									17	7	13
Interest expense									12,342	12,031	10,908
Salaries and employee benefits									607	588	489
Legal and professional									3,093	2,020	1,700
Other non-interest expense									1,889	2,013	1,761
Total expense									17,931	16,652	14,858
Income (loss) before income taxes and equity in undistributed income of subsidiary									(3,962)	(2,705)	(1,066)
Income tax expense									(861)	(587)	(371)
Income before income taxes									(3,101)	(2,118)	(695)
Equity in undistributed income of subsidiary									323,783	300,758	194,118
Net income									320,682	298,640	193,423
Preferred stock dividends									9,750	9,750	9,750
Net income available to common stockholders									$ 310,932	$ 288,890	$ 183,673