v3.26.3
DESCRIPTION OF BUSINESS, BASIS OF PRESENTATION AND ACCOUNTING POLICIES - Narrative (Details) - USD ($)
$ in Millions
Sep. 30, 2026
Aug. 20, 2026
Dec. 31, 2025
Business Combination [Line Items]      
Goodwill resulting from Santander's acquisition $ 9,245   $ 2,767
SHUSA      
Business Combination [Line Items]      
Goodwill resulting from Santander's acquisition   $ 6,478