Loans - Credit Card: Net Charge-Offs (Detail) (Credit Card, USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Net charge-offs	$ 2,728	$ 3,285
Percentage annualized net charge-off by average loans held for investment	3.46%	4.15%
Domestic
Financing Receivable, Allowance for Credit Losses [Line Items]
Net charge-offs	2,445	2,904
Percentage annualized net charge-off by average loans held for investment	3.43%	4.08%
International
Financing Receivable, Allowance for Credit Losses [Line Items]
Net charge-offs	$ 283	$ 381
Percentage annualized net charge-off by average loans held for investment	3.69%	4.78%