Loans - Credit Card Loan Portfolio, Payment Status of FDMs and Defaults of FDMs (Details) - Credit card $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) loan_payment	Sep. 30, 2024 USD ($)
Financing Receivable, Modified [Line Items]
Amortized cost of FDMs during the last 12 months	$ 1,642	$ 868	$ 1,642	$ 868
FDM's that defaulted	56	0	$ 75	0
Number of payments past due considered payment default for modified loans | loan_payment			2
Current and less than 30 days past due and still accruing
Financing Receivable, Modified [Line Items]
Amortized cost of FDMs during the last 12 months	1,438	757	$ 1,438	757
30–89 days past due and still accruing
Financing Receivable, Modified [Line Items]
Amortized cost of FDMs during the last 12 months	134	70	134	70
90 or more days past due and still accruing
Financing Receivable, Modified [Line Items]
Amortized cost of FDMs during the last 12 months	$ 70	$ 41	$ 70	$ 41