Loans - Consumer, Excluding Credit Card Loan Portfolio, Auto and Other, Nonaccrual Loans and Other Credit Quality Indicators (Details) (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Retained loans	$ 1,089,598,000,000	$ 1,010,206,000,000	$ 960,506,000,000
Consumer, excluding credit card
Financing Receivable, Credit Quality Indicator [Line Items]
Retained loans	300,753,000,000	295,556,000,000	$ 302,127,000,000
Consumer, excluding credit card | Auto and other
Financing Receivable, Credit Quality Indicator [Line Items]
Nonaccrual loans	129,000,000	119,000,000
Retained loans	63,192,000,000	70,761,000,000
90 or more days past due and still accruing		0
Consumer, excluding credit card | Auto and other | Paycheck Protection Program (PPP)
Financing Receivable, Credit Quality Indicator [Line Items]
Retained loans	350,000,000	5,400,000,000
Consumer, excluding credit card | Auto and other | Paycheck Protection Program (PPP) | 90 or more days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Nonaccrual loans	76,000,000	35,000,000
Retained loans	101,000,000	506,000,000
Consumer, excluding credit card | Auto and other | Not U.S. government-guaranteed
Financing Receivable, Credit Quality Indicator [Line Items]
90 or more days past due and still accruing	0
Consumer, excluding credit card | Auto and other | California
Financing Receivable, Credit Quality Indicator [Line Items]
Retained loans	9,689,000,000	11,163,000,000
Consumer, excluding credit card | Auto and other | Texas
Financing Receivable, Credit Quality Indicator [Line Items]
Retained loans	7,216,000,000	7,859,000,000
Consumer, excluding credit card | Auto and other | Florida
Financing Receivable, Credit Quality Indicator [Line Items]
Retained loans	4,847,000,000	4,901,000,000
Consumer, excluding credit card | Auto and other | New York
Financing Receivable, Credit Quality Indicator [Line Items]
Retained loans	4,345,000,000	5,848,000,000
Consumer, excluding credit card | Auto and other | Illinois
Financing Receivable, Credit Quality Indicator [Line Items]
Retained loans	2,839,000,000	2,930,000,000
Consumer, excluding credit card | Auto and other | New Jersey
Financing Receivable, Credit Quality Indicator [Line Items]
Retained loans	2,219,000,000	2,355,000,000
Consumer, excluding credit card | Auto and other | Pennsylvania
Financing Receivable, Credit Quality Indicator [Line Items]
Retained loans	1,822,000,000	2,004,000,000
Consumer, excluding credit card | Auto and other | Georgia
Financing Receivable, Credit Quality Indicator [Line Items]
Retained loans	1,708,000,000	1,748,000,000
Consumer, excluding credit card | Auto and other | Ohio
Financing Receivable, Credit Quality Indicator [Line Items]
Retained loans	1,603,000,000	1,843,000,000
Consumer, excluding credit card | Auto and other | Louisiana
Financing Receivable, Credit Quality Indicator [Line Items]
Retained loans	1,576,000,000	1,801,000,000
Consumer, excluding credit card | Auto and other | All other
Financing Receivable, Credit Quality Indicator [Line Items]
Retained loans	$ 25,328,000,000	$ 28,309,000,000