| Document and Entity Information | Mar. 12, 2021 |
| Entity Listings [Line Items] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Mar. 12, 2021 |
| Entity Registrant Name | HUNTINGTON BANCSHARES INC/MD |
| Entity Incorporation, State or Country Code | MD |
| Entity File Number | 001-34073 |
| Entity Tax Identification Number | 31-0724920 |
| Entity Address, Address Line One | 41 South High Street |
| Entity Address, City or Town | Columbus |
| Entity Address, State or Province | OH |
| Entity Address, Postal Zip Code | 43287 |
| City Area Code | 614 |
| Local Phone Number | 480-2265 |
| Written Communications | true |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0000049196 |
| Depositary Shares (each representing a 1/40th interest in a share of 5.875% Series C Non-Cumulative, perpetual preferred stock) [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | Depositary Shares (each representing a 1/40th interest in a share of 5.875% Series C Non-Cumulative, perpetual preferred stock) |
| Trading Symbol | HBANN |
| Security Exchange Name | NASDAQ |
| Depositary Shares (each representing a 1/40th interest in a share of 6.250% Series D Non-Cumulative, perpetual preferred stock) [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | Depositary Shares (each representing a 1/40th interest in a share of 6.250% Series D Non-Cumulative, perpetual preferred stock) |
| Trading Symbol | HBANO |
| Security Exchange Name | NASDAQ |
| Depositary Shares (each representing a 1/40th interest in a share of 4.500% Series H Non-Cumulative, perpetual preferred stock) [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | Depositary Shares (each representing a 1/40th interest in a share of 4.500% Series H Non-Cumulative, perpetual preferred stock) |
| Trading Symbol | HBANP |
| Security Exchange Name | NASDAQ |
| Common Stock [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | Common Stock-Par Value $0.01 per Share |
| Trading Symbol | HBAN |
| Security Exchange Name | NASDAQ |
