v3.26.1
Employee Benefit Plan, Schedule, Asset Held for Investment (Details) - EBP 401K - USD ($)
shares in Thousands, $ in Thousands
Dec. 31, 2025
Dec. 31, 2024
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Note Receivable from Participant $ 22,256 $ 20,283
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value 1,277,911 1,194,074
Fair Value, Inputs, Level 1    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 1,277,911 1,194,074
Fair Value, Inputs, Level 1 | Common Stock | Cullen/Frost Bankers, Inc.    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 2,695  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 341,230 378,145
Fair Value, Inputs, Level 1 | Mutual Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 936,681 $ 815,929
Fair Value, Inputs, Level 1 | Mutual Fund | American Beacon Stephens Small Cap Growth Fund R6    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 89  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 1,367  
Fair Value, Inputs, Level 1 | Mutual Fund | American Funds Balanced R6    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 1,501  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 56,287  
Fair Value, Inputs, Level 1 | Mutual Fund | DFA Large CAP International I    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 1,257  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 43,542  
Fair Value, Inputs, Level 1 | Mutual Fund | Dodge & Cox Stock I    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 1,291  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 21,411  
Fair Value, Inputs, Level 1 | Mutual Fund | Fidelity 500 Index    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 587  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 139,614  
Fair Value, Inputs, Level 1 | Mutual Fund | Fidelity Blue Chip Growth K6    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 2,174  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 96,179  
Fair Value, Inputs, Level 1 | Mutual Fund | Fidelity Emerging Markets Index    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 1,002  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 13,701  
Fair Value, Inputs, Level 1 | Mutual Fund | Fidelity Freedom Index 2020 IPR    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 841  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 14,187  
Fair Value, Inputs, Level 1 | Mutual Fund | Fidelity Freedom Index 2025 IPR    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 1,030  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 20,933  
Fair Value, Inputs, Level 1 | Mutual Fund | Fidelity Freedom Index 2030 IPR    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 1,312  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 29,665  
Fair Value, Inputs, Level 1 | Mutual Fund | Fidelity Freedom Index 2035 IPR    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 1,230  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 32,741  
Fair Value, Inputs, Level 1 | Mutual Fund | Fidelity Freedom Index 2040 IPR    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 962  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 27,720  
Fair Value, Inputs, Level 1 | Mutual Fund | Fidelity Freedom Index 2045 IPR    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 812  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 25,051  
Fair Value, Inputs, Level 1 | Mutual Fund | Fidelity Freedom Index 2050 IPR    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 778  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 24,062  
Fair Value, Inputs, Level 1 | Mutual Fund | Fidelity Freedom Index 2055 IPR    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 949  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 24,155  
Fair Value, Inputs, Level 1 | Mutual Fund | Fidelity Freedom Index 2060 IPR    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 721  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 15,550  
Fair Value, Inputs, Level 1 | Mutual Fund | Fidelity Freedom Index 2065 IPR    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 594  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 10,378  
Fair Value, Inputs, Level 1 | Mutual Fund | Fidelity Freedom Index 2070 IPR    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 68  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 840  
Fair Value, Inputs, Level 1 | Mutual Fund | Fidelity Freedom Index RET IPR    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 528  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 6,520  
Fair Value, Inputs, Level 1 | Mutual Fund | Fidelity Small Cap Index Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 831  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 25,692  
Fair Value, Inputs, Level 1 | Mutual Fund | Fidelity State Bond Index    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 208  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 2,105  
Fair Value, Inputs, Level 1 | Mutual Fund | Fidelity US Bond Index    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 1,545  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 16,320  
Fair Value, Inputs, Level 1 | Mutual Fund | Fidelity Money Market Government Institutional    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 51,661  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 51,662  
Fair Value, Inputs, Level 1 | Mutual Fund | Frost Growth Equity Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 5,055  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 73,858  
Fair Value, Inputs, Level 1 | Mutual Fund | Frost Low Duration Bond Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 1,039  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 10,344  
Fair Value, Inputs, Level 1 | Mutual Fund | Frost Total Return Bond Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 3,945  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 38,227  
Fair Value, Inputs, Level 1 | Mutual Fund | John Hancock Disciplined Value Mid Cap Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 1,096  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 30,107  
Fair Value, Inputs, Level 1 | Mutual Fund | MFS Value Fund R6    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 730  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 36,456  
Fair Value, Inputs, Level 1 | Mutual Fund | PIMCO Real Return Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 755  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 7,831  
Fair Value, Inputs, Level 1 | Mutual Fund | T Rowe Price Mid Cap Growth Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 328  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 32,015  
Fair Value, Inputs, Level 1 | Mutual Fund | Victory Sycamore Small Company Opportunity Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Number of Shares 180  
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value $ 8,161