Loans - Trouble Debt Restructurings (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Loans Modified	$ 495	$ 179	$ 1,629	$ 601
Credit Card
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Loans Modified	$ 106	$ 65	$ 289	$ 208
Credit Card | Reduced Interest Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	100.00%	100.00%	100.00%	100.00%
Average Rate Reduction	19.77%	20.90%	19.63%	21.26%
Consumer Banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Loans Modified	$ 276	$ 89	$ 796	$ 270
Consumer Banking | Reduced Interest Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	64.00%	48.00%	56.00%	40.00%
Average Rate Reduction	8.45%	8.54%	8.59%	8.72%
Consumer Banking | Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	97.00%	92.00%	97.00%	93.00%
Average Term Extension (Months)	5 months	4 months	4 months	4 months
Consumer Banking | Principal Forgiveness
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivables, Impaired, Write-down Percentage of Troubled Debt Restructuring Activity				0.00%
Gross Balance Reduction				$ 1
Consumer Banking | Auto
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Loans Modified	$ 275	$ 89	$ 794	$ 269
Consumer Banking | Auto | Reduced Interest Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	64.00%	48.00%	56.00%	40.00%
Average Rate Reduction	8.45%	8.54%	8.59%	8.74%
Consumer Banking | Auto | Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	97.00%	92.00%	97.00%	93.00%
Average Term Extension (Months)	5 months	4 months	4 months	4 months
Consumer Banking | Auto | Principal Forgiveness
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivables, Impaired, Write-down Percentage of Troubled Debt Restructuring Activity				0.00%
Gross Balance Reduction				$ 1
Consumer Banking | Retail banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Loans Modified	$ 1		$ 2	$ 1
Consumer Banking | Retail banking | Reduced Interest Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity				20.00%
Average Rate Reduction				2.55%
Consumer Banking | Retail banking | Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	60.00%		76.00%	36.00%
Average Term Extension (Months)	14 months		13 months	67 months
Commercial Banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Loans Modified	$ 113	$ 25	$ 544	$ 123
Commercial Banking | Reduced Interest Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	20.00%	12.00%	6.00%	2.00%
Average Rate Reduction	0.78%	2.50%	0.35%	1.29%
Commercial Banking | Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	99.00%	100.00%	72.00%	61.00%
Average Term Extension (Months)	15 months	11 months	13 months	11 months
Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Loans Modified	$ 38	$ 21	$ 302	$ 41
Commercial Banking | Commercial and multifamily real estate | Reduced Interest Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	58.00%	14.00%	10.00%	7.00%
Average Rate Reduction	0.78%	2.50%	0.35%	1.29%
Commercial Banking | Commercial and multifamily real estate | Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	100.00%	100.00%	80.00%	100.00%
Average Term Extension (Months)	11 months	12 months	13 months	13 months
Commercial Banking | Commercial And Industrial [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Loans Modified	$ 75	$ 4	$ 242	$ 82
Commercial Banking | Commercial And Industrial [Member] | Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	98.00%	100.00%	62.00%	41.00%
Average Term Extension (Months)	17 months	4 months	14 months	8 months
Domestic credit card: | Credit Card
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Loans Modified	$ 77	$ 37	$ 196	$ 114
Domestic credit card: | Credit Card | Reduced Interest Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	100.00%	100.00%	100.00%	100.00%
Average Rate Reduction	16.79%	15.80%	15.76%	16.00%
International card businesses: | Credit Card
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Loans Modified	$ 29	$ 28	$ 93	$ 94
International card businesses: | Credit Card | Reduced Interest Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	100.00%	100.00%	100.00%	100.00%
Average Rate Reduction	27.52%	27.75%	27.73%	27.66%