| Cover Page | Mar. 04, 2024 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Mar. 04, 2024 |
| Entity Registrant Name | Santander Holdings USA, Inc. |
| Entity Incorporation, State or Country Code | VA |
| Entity File Number | 1-16581 |
| Entity Tax Identification Number | 23-2453088 |
| Entity Address, Address Line One | 75 State Street |
| Entity Address, City or Town | Boston |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 02109 |
| City Area Code | 800 |
| Local Phone Number | 493-8219 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Not Applicable |
| Trading Symbol | Not Applicable |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Entity Central Index Key | 0000811830 |
