Stockholders' Equity - Components of Other Comprehensive Income Loss and Related Tax Impact (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Before Tax
Net unrealized gains (losses) on securities available for sale	$ 46	$ 296
Net changes in securities held to maturity	36	33
Net unrealized gains (losses) on cash flow hedges	(104)	600
Foreign currency translation adjustments	4	26
Other	7	(17)
Other comprehensive income before taxes	(11)	938
Provision (Benefit)
Net unrealized gains (losses) on securities available for sale	10	109
Net changes in securities held to maturity	13	12
Net unrealized gains (losses) on cash flow hedges	(38)	223
Foreign currency translation adjustments	(13)	25
Other	2	(6)
Other comprehensive income (loss), provision (benefit)	(26)	363
After Tax
Net unrealized gains (losses) on securities available for sale	36	187
Net changes in securities held to maturity	23	21
Net unrealized gains (losses) on cash flow hedges	(66)	377
Foreign currency translation adjustments	17	1
Other	5	(11)
Other comprehensive income (loss), net of tax	$ 15	$ 575

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