Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 923	$ 618	$ 2,572	$ 1,757	[1]
Change in net unrealized gain (loss) on available for sale securities:
Net unrealized gain (loss)	(43)	0	(184)	81
Reclassification of net unrealized loss transferred to held to maturity	0	0	0	227
Other reclassifications included in other revenue	0	0	0	(7)
Change in net unrealized gain (loss) on held to maturity securities:
Reclassification of net unrealized loss transferred from available for sale	0	0	0	(227)
Amortization of amounts previously recorded upon transfer from available for sale	8	10	26	21
Other	0	0	0	(3)
Other comprehensive income (loss), before tax	(35)	10	(158)	92
Income tax effect	9	(4)	39	(35)
Other comprehensive income (loss), net of tax	(26)	6	(119)	57
Comprehensive Income	$ 897	$ 624	$ 2,453	$ 1,814

[1] Adjusted for the retrospective adoption of ASU 2016-18. See Note 2.