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Regulatory and Capital Adequacy - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions | 12 Months Ended | 36 Months Ended |
--- | --- | --- | ---
Dec. 31, 2021 | Dec. 31, 2025 | Dec. 31, 2024
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |  |  |
Regulatory capital adjustments, net of tax, CECL transition | $ 2,400 |  |
Common equity tier one capital ratio, CECL transition |  |  | 13.50%
Common equity tier one capital ratio, excluding CECL transition adjustment |  |  | 13.30%
Forecast |  |  |
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |  |  |
Regulatory capital adjustments, net of tax, CECL transition, phased in amount |  | $ 600 |
Capital One Bank (USA), N.A. |  |  |
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |  |  |
Funds available for dividend payments |  |  | $ 8,900
Fund available for dividend payments, per share (in USD per share) |  |  | $ 0.60

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Publisher FASB -URI https://asc.fasb.org/1943274/2147477270/942-505-50-1B Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147477270/942-505-50-1 + Details
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