Loans - Credit Card Loan Portfolio, Other Credit Quality Indicators (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Loans and Leases Receivable Disclosure [Line Items]
Retained loans	$ 1,089,598	$ 1,010,206	$ 960,506
Credit card
Loans and Leases Receivable Disclosure [Line Items]
Retained loans	$ 185,175	$ 154,296
Percentage of portfolio based on carrying value with estimated refreshed FICO scores, Equal to or greater than 660	86.80%	88.50%
Percentage of portfolio based on carrying value with estimated refreshed FICO scores, Less than 660	13.00%	11.30%
Percentage of portfolio based on carrying value with estimated refreshed FICO scores, No FICO available	0.20%	0.20%
Credit card | California
Loans and Leases Receivable Disclosure [Line Items]
Retained loans	$ 28,154	$ 23,030
Credit card | Texas
Loans and Leases Receivable Disclosure [Line Items]
Retained loans	19,171	15,879
Credit card | New York
Loans and Leases Receivable Disclosure [Line Items]
Retained loans	15,046	12,652
Credit card | Florida
Loans and Leases Receivable Disclosure [Line Items]
Retained loans	12,905	10,412
Credit card | Illinois
Loans and Leases Receivable Disclosure [Line Items]
Retained loans	10,089	8,530
Credit card | New Jersey
Loans and Leases Receivable Disclosure [Line Items]
Retained loans	7,643	6,367
Credit card | Ohio
Loans and Leases Receivable Disclosure [Line Items]
Retained loans	5,792	4,923
Credit card | Pennsylvania
Loans and Leases Receivable Disclosure [Line Items]
Retained loans	5,517	4,708
Credit card | Colorado
Loans and Leases Receivable Disclosure [Line Items]
Retained loans	5,493	4,573
Credit card | Arizona
Loans and Leases Receivable Disclosure [Line Items]
Retained loans	4,487	3,668
Credit card | All other
Loans and Leases Receivable Disclosure [Line Items]
Retained loans	$ 70,878	$ 59,554