Reserves for Credit Losses - Changes in Other Loan Reserve (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provisions for credit losses	$ 1,150	$ 1,269
Other Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	194	126	$ 126
Provisions for credit losses	105	53
Net write-offs	(62)		(207)
Other	0	0
Ending Balance	244	136	$ 194
Other Loans | Principal
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Net write-offs	(53)	(42)
Recoveries	7	4
Other Loans | Interest and fees
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Net write-offs	$ (2)	$ (1)