Loans - Credit Card: Net Charge-Offs (Detail) - Credit Card Portfolio Segment [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Net charge-offs	$ 2,918	$ 2,728
Percentage annualized net charge-off by average loans held for investment	3.36%	3.46%
Geographic Distribution, Domestic [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Net charge-offs	$ 2,718	$ 2,445
Percentage annualized net charge-off by average loans held for investment	3.45%	3.43%
Geographic Distribution, Foreign [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Net charge-offs	$ 200	$ 283
Percentage annualized net charge-off by average loans held for investment	2.50%	3.69%