Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net Income	$ 866	$ 575	$ 1,649	$ 1,139	[1]
Change in net unrealized gain (loss) on available for sale securities:
Net unrealized gain (loss)	(33)	29	(141)	81
Reclassification of net unrealized loss transferred to held to maturity	0	0	0	227
Other reclassifications included in other revenue	0	(6)	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	9	9	18	11
Other	0	0	0	(3)
Other comprehensive income (loss), before tax	(24)	32	(123)	82
Income tax effect	6	(12)	30	(31)
Other comprehensive income (loss), net of tax	(18)	20	(93)	51
Comprehensive Income	$ 848	$ 595	$ 1,556	$ 1,190

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