Loans - Credit Card: Net Charge-Offs (Detail) - Credit Card Portfolio Segment [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Net charge-offs	$ 655	$ 572	$ 2,077	$ 2,037
Percentage annualized net charge-off by average loans held for investment	2.96%	2.88%	3.26%	3.48%
Geographic Distribution, Domestic [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Net charge-offs	$ 619	$ 508	$ 1,933	$ 1,818
Percentage annualized net charge-off by average loans held for investment	3.08%	2.83%	3.35%	3.45%
Geographic Distribution, Foreign [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Net charge-offs	$ 36	$ 64	$ 144	$ 219
Percentage annualized net charge-off by average loans held for investment	1.80%	3.32%	2.41%	3.81%