Loans - 90+ Day Delinquent Loans Accruing Interest and Nonperforming Loans (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days Past Due and Accruing	$ 1,116	$ 1,291
Nonperforming Loans	772	867
Percent 90 days past due and still accruing	0.55%	0.65%
Percent nonperforming loans	0.38%	0.44%
Credit Card
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days Past Due and Accruing	1,109	1,283
Nonperforming Loans	74	88
Credit Card | Domestic
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days Past Due and Accruing	1,033	1,187
Nonperforming Loans	0	0
Credit Card | International
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days Past Due and Accruing	76	96
Nonperforming Loans	74	88
Consumer Banking
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days Past Due and Accruing	1	2
Nonperforming Loans	521	611
Consumer Banking | Auto
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days Past Due and Accruing	0	0
Nonperforming Loans	177	194
Consumer Banking | Home loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days Past Due and Accruing	0	0
Nonperforming Loans	325	376
Consumer Banking | Retail banking
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days Past Due and Accruing	1	2
Nonperforming Loans	19	41
Commercial Banking
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days Past Due and Accruing	6	6
Nonperforming Loans	161	149
Commercial Banking | Total commercial lending
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days Past Due and Accruing	6	6
Nonperforming Loans	157	145
Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days Past Due and Accruing	4	2
Nonperforming Loans	60	52
Commercial Banking | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days Past Due and Accruing	2	4
Nonperforming Loans	97	93
Commercial Banking | Small-ticket commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days Past Due and Accruing	0	0
Nonperforming Loans	4	4
Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days Past Due and Accruing	0	0
Nonperforming Loans	$ 16	$ 19