Accumulated Other Comprehensive Income (Components of Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Other comprehensive income (loss) before tax
Net unrealized gain (loss)	$ 97	$ 51	$ 7,361	$ 496
Other reclassifications included in other revenue	(3)	(1)	(3)	(5)
Amortization of amounts previously recorded upon transfer to held to maturity from available for sale	0	10	0	30
Other	0	0	1	0
Other comprehensive income (loss), before tax	94	60	7,359	521
Tax Effect
Net unrealized gain (loss)	(20)	(12)	(1,762)	(119)
Other reclassifications included in other revenue	1	0	1	1
Amortization of amounts previously recorded upon transfer to held to maturity from available for sale	0	(3)	0	(7)
Other			0	0
Other comprehensive income (loss)	(19)	(15)	(1,761)	(125)
Net of Tax
Net unrealized gain (loss)	77	39	5,599	377
Other reclassifications included in other revenue	(2)	(1)	(2)	(4)
Amortization of amounts previously recorded upon transfer from available for sale	0	7	0	23
Other			1	0
Other comprehensive income (loss), net of tax	$ 75	$ 45	$ 5,598	$ 396