Stockholders' Equity - Other Comprehensive Income (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Before Tax
Net unrealized gains (losses) on securities available for sale	$ 1	$ 132	$ 1,903	$ 874
Net unrealized gains (losses) on hedging relationships	(231)	249	1,653	1,322
Foreign currency translation adjustments	4	9	3	61
Net changes in securities held to maturity	0	10	0	26
Other	(2)	(2)	(2)	(5)
Other comprehensive income (loss), before tax	(228)	398	3,557	2,278
Provision (Benefit)
Net unrealized gains (losses) on securities available for sale	0	32	456	210
Net unrealized gains (losses) on hedging relationships	(56)	60	397	319
Foreign currency translation adjustments	(24)	21	19	28
Net changes in securities held to maturity	0	2	0	6
Other	0	0	0	(1)
Other comprehensive income (loss), provision (benefit)	(80)	115	872	562
After Tax
Net unrealized gains (losses) on securities available for sale	1	100	1,447	664
Net unrealized gains (losses) on hedging relationships	(175)	189	1,256	1,003
Foreign currency translation adjustments	28	(12)	(16)	33
Net changes in securities held to maturity	0	8	0	20
Other	(2)	(2)	(2)	(4)
Other comprehensive income (loss), net of tax	$ (148)	$ 283	$ 2,685	$ 1,716

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