Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Consolidated Statements of Comprehensive Income [Abstract]
Net income	$ 1,889	$ 1,447	$ 1,321
Change in net unrealized gain (loss) on available for sale securities:
Net unrealized gain (loss)	(44)	(477)	255
Reclassification of impairment charges included in net impairment losses on securities			1
Other reclassifications included in other revenue	(4)		(7)
Other	1
Other comprehensive income (loss), before tax	(47)	(477)	249
Income tax effect	18	178	(93)
Other comprehensive income (loss), net of tax	(29)	(299)	156
Comprehensive Income	$ 1,860	$ 1,148	$ 1,477