Loans - Credit Card Loan Portfolio, Payment Status of FDMs and Defaults of FDMs (Details) - Credit card $ in Millions	3 Months Ended
	Mar. 31, 2026 USD ($) loan_payment	Mar. 31, 2025 USD ($)
Financing Receivable, Modified [Line Items]
Amortized cost of FDMs during the last 12 months	$ 2,456	$ 1,045
FDM's that defaulted	$ 99	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	$ 2,139	915
30–89 days past due and still accruing
Financing Receivable, Modified [Line Items]
Amortized cost of FDMs during the last 12 months	191	83
90 or more days past due and still accruing
Financing Receivable, Modified [Line Items]
Amortized cost of FDMs during the last 12 months	$ 126	$ 47