Loans - Trouble Debt Restructurings (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Loans Modified	$ 505	$ 262
Credit Card
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Loans Modified	96	83
Consumer Banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Loans Modified	240	115
Consumer Banking | Auto
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Loans Modified	239	115
Consumer Banking | Retail banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Loans Modified	1
Commercial Banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Loans Modified	169	64
Commercial Banking | Commercial And Industrial [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Loans Modified	38	44
Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Loans Modified	$ 131	$ 20
Reduced Interest Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	47.00%	47.00%
Average Rate Reduction	17.98%	33.62%
Reduced Interest Rate | Credit Card
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	100.00%	100.00%
Average Rate Reduction	19.40%	21.58%
Reduced Interest Rate | Consumer Banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	55.00%	35.00%
Average Rate Reduction	8.80%	9.02%
Reduced Interest Rate | Consumer Banking | Auto
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	55.00%	35.00%
Average Rate Reduction	8.80%	9.02%
Reduced Interest Rate | Consumer Banking | Retail banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	0.00%
Average Rate Reduction	0.00%
Reduced Interest Rate | Commercial Banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	6.00%	0.00%
Average Rate Reduction	0.59%	0.00%
Reduced Interest Rate | Commercial Banking | Commercial And Industrial [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	0.00%	0.00%
Average Rate Reduction	0.00%	0.00%
Reduced Interest Rate | Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	7.00%	0.00%
Average Rate Reduction	0.59%	0.00%
Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	69.00%	54.00%
Average Term Extension (Months)	7 months	5 months
Term Extension | Credit Card
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	0.00%	0.00%
Average Term Extension (Months)	0 months	0 months
Term Extension | Consumer Banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	97.00%	95.00%
Average Term Extension (Months)	4 months	3 months
Term Extension | Consumer Banking | Auto
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	97.00%	95.00%
Average Term Extension (Months)	4 months	3 months
Term Extension | Consumer Banking | Retail banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	100.00%
Average Term Extension (Months)	6 months
Term Extension | Commercial Banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	68.00%	48.00%
Average Term Extension (Months)	11 months	10 months
Term Extension | Commercial Banking | Commercial And Industrial [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	86.00%	25.00%
Average Term Extension (Months)	10 months	2 months
Term Extension | Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	62.00%	100.00%
Average Term Extension (Months)	12 months	14 months
Domestic credit card: | Credit Card
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Loans Modified	$ 62	$ 44
Domestic credit card: | Reduced Interest Rate | Credit Card
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	100.00%	100.00%
Average Rate Reduction	14.67%	16.12%
Domestic credit card: | Term Extension | Credit Card
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	0.00%	0.00%
Average Term Extension (Months)	0 months	0 months
International card businesses: | Credit Card
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Loans Modified	$ 34	$ 39
International card businesses: | Reduced Interest Rate | Credit Card
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	100.00%	100.00%
Average Rate Reduction	28.00%	27.74%
International card businesses: | Term Extension | Credit Card
Financing Receivable, Troubled Debt Restructuring [Line Items]
% of TDR Activity	0.00%	0.00%
Average Term Extension (Months)	0 months	0 months