Stockholders' Equity - Components of Other Comprehensive Income Loss and Related Tax Impact (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Before Tax
Net unrealized gains (losses) on securities available for sale	$ 384	$ (771)
Net changes in securities held to maturity	7	559
Net unrealized gains (losses) on cash flow hedges	365	(418)
Foreign currency translation adjustments	19	(12)
Other	(2)	(1)
Other comprehensive income before taxes	773	(643)
Provision (Benefit)
Net unrealized gains (losses) on securities available for sale	92	(186)
Net changes in securities held to maturity	1	134
Net unrealized gains (losses) on cash flow hedges	88	(100)
Foreign currency translation adjustments	(11)	(19)
Other	0	0
Other comprehensive income (loss), provision (benefit)	170	(171)
After Tax
Net unrealized gains (losses) on securities available for sale	292	(585)
Net changes in securities held to maturity	6	425
Net unrealized gains (losses) on cash flow hedges	277	(318)
Foreign currency translation adjustments	30	7
Other	(2)	(1)
Other comprehensive income (loss), net of tax	$ 603	$ (472)

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