Reserves for Credit Losses - Changes in Other Loan Reserve (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provisions for credit losses	$ 1,287	$ 1,356	$ 3,842	$ 3,893
Other Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	272	140	194	126	$ 126
Provisions for credit losses	62	60	245	162
Net write-offs			(178)		(207)
Other	0	0	1	0
Ending Balance	287	154	287	154	$ 194
Other Loans | Principal
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Net write-offs	(45)	(44)	(146)	(129)
Recoveries	10	5	25	14
Other Loans | Interest and fees
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Net write-offs	$ (2)	$ (2)	$ (7)	$ (5)