Loans - Credit Card: Net Charge-Offs (Detail) - Credit Card Portfolio Segment [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Net charge-offs	$ 950	$ 719
Percentage annualized net charge-off by average loans held for investment	4.09%	3.48%
Geographic Distribution, Domestic [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Net charge-offs	$ 887	$ 664
Percentage annualized net charge-off by average loans held for investment	4.16%	3.55%
Geographic Distribution, Foreign [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Net charge-offs	$ 63	$ 55
Percentage annualized net charge-off by average loans held for investment	3.24%	2.80%