Long-Term Debt (Details 1) - USD ($) $ in Thousands	Mar. 31, 2021	Jan. 31, 2014	Sep. 21, 2012
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Trust preferred securities issued		$ 175,000	$ 111,000
Texas Capital Bancshares Statutory Trust I
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Trust preferred securities issued	$ 10,310
Texas Capital Statutory Trust II
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Trust preferred securities issued	10,310
Texas Capital Statutory Trust III
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Trust preferred securities issued	25,774
Texas Capital Statutory Trust IV
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Trust preferred securities issued	25,774
Texas Capital Statutory Trust V
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Trust preferred securities issued	$ 41,238