Loans - 90+ Day Delinquent Loans Accruing Interest and Nonperforming Loans (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Financing Receivable, Past Due [Line Items]
90 Days Past Due and Accruing	$ 1,207		$ 1,302
Nonperforming Loans	924		995
Nonperforming Loans Without an Allowance	$ 485		$ 449
Percentage, 90 Days Past Due and Accruing	0.50%		0.50%
Percentage, Nonperforming Loans	0.40%		0.40%
Percentage, Nonperforming Loans Without an Allowance	0.20%		0.20%
Interest income for loans classified as nonperforming	$ 1	$ 2
Credit Card
Financing Receivable, Past Due [Line Items]
90 Days Past Due and Accruing	1,207		$ 1,251
Nonperforming Loans	14		21
Nonperforming Loans Without an Allowance	0		0
Credit Card \| Domestic credit card:
Financing Receivable, Past Due [Line Items]
90 Days Past Due and Accruing	1,120		1,169
Nonperforming Loans Without an Allowance	0		0
Credit Card \| International card businesses:
Financing Receivable, Past Due [Line Items]
90 Days Past Due and Accruing	87		82
Nonperforming Loans	14		21
Nonperforming Loans Without an Allowance	0		0
Consumer Banking
Financing Receivable, Past Due [Line Items]
90 Days Past Due and Accruing	0		0
Nonperforming Loans	228		324
Nonperforming Loans Without an Allowance	11		0
Consumer Banking \| Auto
Financing Receivable, Past Due [Line Items]
90 Days Past Due and Accruing	0		0
Nonperforming Loans	192		294
Nonperforming Loans Without an Allowance	0		0
Consumer Banking \| Retail banking
Financing Receivable, Past Due [Line Items]
90 Days Past Due and Accruing	0		0
Nonperforming Loans	36		30
Nonperforming Loans Without an Allowance	11		0
Commercial Banking
Financing Receivable, Past Due [Line Items]
90 Days Past Due and Accruing	0		51
Nonperforming Loans	682		650
Nonperforming Loans Without an Allowance	474		449
Commercial Banking \| Commercial and multifamily real estate
Financing Receivable, Past Due [Line Items]
90 Days Past Due and Accruing	0		51
Nonperforming Loans	234		200
Nonperforming Loans Without an Allowance	219		184
Commercial Banking \| Commercial and industrial
Financing Receivable, Past Due [Line Items]
90 Days Past Due and Accruing	0		0
Nonperforming Loans	448		450
Nonperforming Loans Without an Allowance	$ 255		$ 265

Financing Receivable, Nonaccrual, No Allowance, Percent Past Due

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Financing Receivable, Percent 90 Days Past Due and Still Accruing

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Amount of financing receivable 90 days or more past due and still accruing.

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