v3.26.3
BORROWINGS - Schedule of Parent Company and Other Subsidiary Borrowings and Debt Obligations (Details) - USD ($)
$ in Millions
Sep. 30, 2026
Dec. 31, 2025
Debt Instrument [Line Items]    
Total Parent Company and subsidiaries' borrowings and other debt obligations $ 42,816 $ 37,102
Parent Company and Subsidiaries    
Debt Instrument [Line Items]    
Total Parent Company and subsidiaries' borrowings and other debt obligations 42,816 37,102
Subsidiaries | CLNs, due various dates through November 2035    
Debt Instrument [Line Items]    
Balance $ 690 $ 0
Effective Rate 6.84% 0.00%
Subsidiaries | Short-term borrowing due within one year, maturing through December 2026    
Debt Instrument [Line Items]    
Short-term borrowings $ 475 $ 691
Effective Rate 3.36% 3.61%
Subsidiaries | FHLB advances, maturing through September 2039    
Debt Instrument [Line Items]    
Balance $ 11,609 $ 708
Effective Rate 4.15% 4.16%
Subsidiaries | CLNs, due various dates through February 2052    
Debt Instrument [Line Items]    
Balance $ 1,203 $ 914
Subsidiaries | CLNs, due various dates through February 2052 | Minimum    
Debt Instrument [Line Items]    
Effective Rate 6.09% 6.37%
Subsidiaries | CLNs, due various dates through February 2052 | Maximum    
Debt Instrument [Line Items]    
Effective Rate 19.36% 16.29%
Subsidiaries | Warehouse lines with third parties, maturing through April 2028 | Revolving Credit Facilities with Third Parties    
Debt Instrument [Line Items]    
Balance $ 0 $ 215
Effective Rate 0.00% 4.67%
Subsidiaries | Warehouse lines with Santander, maturing through October 2027 | Revolving Credit Facility With Related Parties    
Debt Instrument [Line Items]    
Balance $ 0 $ 2,000
Effective Rate 0.00% 4.44%
Subsidiaries | Secured structured financings, maturing through May 2034    
Debt Instrument [Line Items]    
Balance $ 12,989 $ 19,751
Subsidiaries | Secured structured financings, maturing through May 2034 | Minimum    
Debt Instrument [Line Items]    
Effective Rate 0.59% 0.58%
Subsidiaries | Secured structured financings, maturing through May 2034 | Maximum    
Debt Instrument [Line Items]    
Effective Rate 6.73% 7.69%
Senior Notes | Senior notes, due various dates through June 2037    
Debt Instrument [Line Items]    
Balance $ 14,420 $ 11,823
Notes payable $ 2,000  
Senior Notes | Senior notes, due various dates through June 2037 | Minimum    
Debt Instrument [Line Items]    
Effective Rate 2.57% 2.57%
Senior Notes | Senior notes, due various dates through June 2037 | Maximum    
Debt Instrument [Line Items]    
Effective Rate 7.73% 7.73%
Senior Notes | CLNs, due various dates through November 2035    
Debt Instrument [Line Items]    
Notes payable $ 1,000  
Subordinated Debt | Subordinated notes, due various dates through September 2035    
Debt Instrument [Line Items]    
Balance $ 1,430 $ 1,000
Subordinated Debt | Subordinated notes, due various dates through September 2035 | Minimum    
Debt Instrument [Line Items]    
Effective Rate 2.88% 2.88%
Subordinated Debt | Subordinated notes, due various dates through September 2035 | Maximum    
Debt Instrument [Line Items]    
Effective Rate 7.18% 7.18%