v3.26.1
Employee Benefit Plan, Fair Value and NAV (Details) - EBP 401K - USD ($)
$ in Thousands
Dec. 31, 2025
Dec. 31, 2024
EBP, Investment, Fair Value and NAV [Line Items]    
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 1,277,911 $ 1,194,074
Fair Value, Inputs, Level 1    
EBP, Investment, Fair Value and NAV [Line Items]    
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value 1,277,911 1,194,074
Fair Value, Inputs, Level 1 | Mutual Fund    
EBP, Investment, Fair Value and NAV [Line Items]    
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value 936,681 815,929
Fair Value, Inputs, Level 1 | Cullen/Frost Bankers, Inc. | Common Stock    
EBP, Investment, Fair Value and NAV [Line Items]    
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 341,230 $ 378,145