XML 70 R53.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Billions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2021 | Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss [Line Items] |  |
Customer Reward Program | $ 6.2 | $ 5.4
Loan origination fees and direct loan origination costs amortization period | 12 months |
Credit Card |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |
Loan origination fees and direct loan origination costs amortization period | 12 months |
Amortization term of annual membership fees | 12 months |

X
- Definition Amortization term of credit card annual membership fees + References No definition available. + Details
Name: | cof_AmortizationTermofAnnualMembershipFees
Namespace Prefix: | cof_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Customer Loyalty Program Liability + References No definition available. + Details
Name: | cof_CustomerLoyaltyProgramLiability
Namespace Prefix: | cof_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Loan Commitment and Origination Fees and Discounts or Premiums, Amortization Period + References No definition available. + Details
Name: | cof_LoanCommitmentandOriginationFeesandDiscountsorPremiumsAmortizationPeriod
Namespace Prefix: | cof_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

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

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=cof_CreditCardPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |