Loans - Credit Card Loan Portfolio, Delinquency Information (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	$ 1,089,598	$ 1,010,206	$ 960,506
Credit card
Loans and Leases Receivable Disclosure [Line Items]
Revolving loans within revolving period	184,379	153,309
Revolving loans converted to term loans	796	987
Total retained loans	$ 185,175	$ 154,296
% of 30 plus days past due to total retained loans, Revolving loans within the revolving period	1.40%	0.99%
% of 30 plus days past due to total retained loans, Revolving loans converted to term loans	12.56%	8.71%
% of 30 plus days past due to total retained loans	1.45%	1.04%
% of 90 plus days past due to total retained loans, Revolving loans within the revolving period	0.67%	0.48%
% of 90 plus days past due to total retained loans, Revolving loans converted to term loans	4.52%	2.74%
% of 90 plus days past due to total retained loans	0.68%	0.50%
Credit card | Current and less than 30 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Revolving loans within revolving period	$ 181,793	$ 151,798
Revolving loans converted to term loans	696	901
Total retained loans	182,489	152,699
Credit card | 30–89 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Revolving loans within revolving period	1,356	770
Revolving loans converted to term loans	64	59
Total retained loans	1,420	829
Credit card | 90 or more days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Revolving loans within revolving period	1,230	741
Revolving loans converted to term loans	36	27
Total retained loans	$ 1,266	$ 768