Loans - Credit Card: Net Charge-Offs (Detail) (Credit Card, USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Net charge-offs	$ 572	$ 734	$ 2,037	$ 2,506
Percentage annualized net charge-off by average loans held for investment	2.88%	3.78%	3.48%	4.20%
Domestic
Financing Receivable, Allowance for Credit Losses [Line Items]
Net charge-offs	508	642	1,818	2,218
Percentage annualized net charge-off by average loans held for investment	2.83%	3.67%	3.45%	4.14%
International
Financing Receivable, Allowance for Credit Losses [Line Items]
Net charge-offs	$ 64	$ 92	$ 219	$ 288
Percentage annualized net charge-off by average loans held for investment	3.32%	4.71%	3.81%	4.79%