| Document and Entity Information | May 05, 2022 |
| Document And Entity Information [Line Items] | |
| Entity Registrant Name | CAPITAL ONE FINANCIAL CORP |
| Amendment Flag | false |
| Entity Central Index Key | 0000927628 |
| Document Type | 8-K |
| Document Period End Date | May 5, 2022 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-13300 |
| Entity Tax Identification Number | 54-1719854 |
| Entity Address, Address Line One | 1680 Capital One Drive |
| Entity Address, City or Town | McLean |
| Entity Address, State or Province | VA |
| Entity Address, Postal Zip Code | 22102 |
| City Area Code | (703) |
| Local Phone Number | 720-1000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Common Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Common Stock (par value $.01 per share) |
| Trading Symbol | COF |
| Security Exchange Name | NYSE |
| Series I Preferred Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Depositary Shares, Each Representing a 1/40th Interest in a Share of Fixed Rate Non-Cumulative Perpetual Preferred Stock, Series I |
| Trading Symbol | COF PRI |
| Security Exchange Name | NYSE |
| Series J Preferred Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Depositary Shares, Each Representing a 1/40th Interest in a Share of Fixed Rate Non-Cumulative Perpetual Preferred Stock, Series J |
| Trading Symbol | COF PRJ |
| Security Exchange Name | NYSE |
| Series K Preferred Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Depositary Shares, Each Representing a 1/40th Interest in a Share of Fixed Rate Non-Cumulative Perpetual Preferred Stock, Series K |
| Trading Symbol | COF PRK |
| Security Exchange Name | NYSE |
| Series L Preferred Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Depositary Shares, Each Representing a 1/40th Interest in a Share of Fixed Rate Non-Cumulative Perpetual Preferred Stock, Series L |
| Trading Symbol | COF PRL |
| Security Exchange Name | NYSE |
| Series N Preferred Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Depositary Shares, Each Representing a 1/40th Interest in a Share of Fixed Rate Non-Cumulative Perpetual Preferred Stock, Series N |
| Trading Symbol | COF PRN |
| Security Exchange Name | NYSE |
| M 0.800 Senior Notes Due 2024 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 0.800% Senior Notes Due 2024 |
| Trading Symbol | COF24 |
| Security Exchange Name | NYSE |
| M 1.650 Senior Notes Due 2029 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 1.650% Senior Notes Due 2029 |
| Trading Symbol | COF29 |
| Security Exchange Name | NYSE |
