v3.26.1
Document and Entity Information
Aug. 25, 2026
Document And Entity Information [Line Items]  
Document Type 8-K
Document Period End Date Aug. 25, 2026
Entity Registrant Name Santander Holdings USA, Inc.
Entity Incorporation State Country Code VA
Entity File Number 1-16581
Entity Tax Identification Number 23-2453088
Entity Address Address Line 1 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
Entity Emerging Growth Company false
Amendment Flag false
Entity Central Index Key 0000811830
Current Fiscal Year End Date --12-31
Depositary Shares Each Representing A 11000th Interest In A Share Of Fixed Rate Reset Non Cumulative Perpetual Preferred Stock Series H [Member]  
Document And Entity Information [Line Items]  
Security 12b Title Depositary Shares, Each Representing a 1/1,000th Interest in a Share of Fixed-Rate Reset Non-Cumulative Perpetual Preferred Stock, Series H
Trading Symbol SNUS PF H
Security Exchange Name NYSE
Depositary Shares Each Representing A 140th Interest In A Share Of Fixed Rate Reset Non Cumulative Perpetual Preferred Stock Series I [Member]  
Document And Entity Information [Line Items]  
Security 12b Title Depositary Shares, Each Representing a 1/40th Interest in a Share of Fixed-Rate Reset Non-Cumulative Perpetual Preferred Stock, Series I
Trading Symbol SNUS PF I
Security Exchange Name NYSE