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v3.25.1

Goodwill and Other Intangible Assets - Additional Information (Details) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2025 | Mar. 31, 2024
Goodwill and Intangible Assets Disclosure [Abstract] |  |
Amortization of intangibles | $ 16 | $ 19

X
- Definition Amortization and impairment of Intangibles + References No definition available. + Details
Name: | cof_AmortizationAndImpairmentOfIntangibles
Namespace Prefix: | cof_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- References No definition available. + Details
Name: | us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration