v3.26.1
Fair Value Measurement (Details) - EBP 002 - USD ($)
Dec. 31, 2025
Dec. 31, 2024
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value $ 13,927,171,474 $ 11,356,035,138
Collective investment trusts    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 11,570,554,417 8,146,645,815
Self-managed funds    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 1,184,635,152 2,124,754,967
Fidelity Brokerage Link    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 553,611,158 381,537,064
Capital One Stock Fund    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 618,370,747 475,332,439
Registered investment companies    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value   227,764,853
Level 1 | Collective investment trusts    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0
Level 1 | Self-managed funds    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 968,849,795 1,491,913,531
Level 1 | Fidelity Brokerage Link    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 553,611,158 381,537,064
Level 1 | Capital One Stock Fund    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 618,370,747 475,332,439
Level 1 | Registered investment companies    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value   227,764,853
Level 2 | Collective investment trusts    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 11,570,554,417 8,146,645,815
Level 2 | Self-managed funds    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 215,785,357 632,841,436
Level 2 | Fidelity Brokerage Link    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0 0
Level 2 | Capital One Stock Fund    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value $ 0 0
Level 2 | Registered investment companies    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value   $ 0