| Document and Entity Information | Dec. 27, 2024 |
| Entity Information [Line Items] | |
| Document Type | 8-K |
| Document Period End Date | Dec. 27, 2024 |
| Entity Registrant Name | KeyCorp |
| Entity File Number | 001-11302 |
| Entity Incorporation State Country Code | OH |
| Entity Tax Identification Number | 34-6542451 |
| Entity Address Address Line 1 | 127 Public Square |
| Entity Address City Or Town | Cleveland |
| Entity Address State Or Province | OH |
| Entity Address Postal Zip Code | 44114-1306 |
| City Area Code | 216 |
| Local Phone Number | 689-3000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Entity Central Index Key | 0000091576 |
| Common Stock [Member] | |
| Entity Information [Line Items] | |
| Security 12b Title | Common Shares, $1 par value |
| Trading Symbol | KEY |
| Security Exchange Name | NYSE |
| Series E Preferred Stock [Member] | |
| Entity Information [Line Items] | |
| Security 12b Title | Depositary Shares (each representing a 1/40th interest in a share of Fixed-to-Floating Rate Perpetual Non-Cumulative Preferred Stock, Series E) |
| Trading Symbol | KEY PrI |
| Security Exchange Name | NYSE |
| Series F Preferred Stock [Member] | |
| Entity Information [Line Items] | |
| Security 12b Title | Depositary Shares (each representing a 1/40th interest in a share of Fixed Rate Perpetual Non-Cumulative Preferred Stock, Series F) |
| Trading Symbol | KEY PrJ |
| Security Exchange Name | NYSE |
| Series G Preferred Stock [Member] | |
| Entity Information [Line Items] | |
| Security 12b Title | Depositary Shares (each representing a 1/40th interest in a share of Fixed Rate Perpetual Non-Cumulative Preferred Stock, Series G) |
| Trading Symbol | KEY PrK |
| Security Exchange Name | NYSE |
| Series H Preferred Stock [Member] | |
| Entity Information [Line Items] | |
| Security 12b Title | Depositary Shares (each representing a 1/40th interest in a share of Fixed Rate Reset Perpetual Non-Cumulative Preferred Stock, Series H) |
| Trading Symbol | KEY PrL |
| Security Exchange Name | NYSE |
