Stockholders' Equity - Components of Other Comprehensive Income Loss and Related Tax Impact (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Before Tax
Net unrealized gains (losses) on securities available for sale	$ 296	$ 190
Net changes in securities held to maturity	33	33
Net unrealized gains (losses) on cash flow hedges	600	258
Foreign currency translation adjustments	26	(41)
Other	(17)	(4)
Other comprehensive income before taxes	938	436
Provision (Benefit)
Net unrealized gains on securities available for sale	109	68
Net changes in securities held to maturity	12	13
Net unrealized gains on cash flow hedges	223	96
Foreign currency translation adjustments	25	43
Other	(6)	(2)
Other comprehensive income (loss), provision (benefit)	363	218
After Tax
Net unrealized gains on securities available for sale	187	122
Net changes in securities held to maturity	21	20
Net unrealized gains on cash flow hedges	377	162
Foreign currency translation adjustments	1	(84)
Other	(11)	(2)
Other comprehensive income (loss), net of tax	$ 575	$ 218