Accumulated Other Comprehensive Income (Components of Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Other comprehensive income (loss) before tax
Net unrealized gain (loss)	$ 2,113	$ 218	$ 7,264	$ 445
Other reclassifications included in other revenue	0	(3)	0	(4)
Amortization of amounts previously recorded upon transfer to held to maturity from available for sale	0	8	0	20
Other	1	0	1	0
Other comprehensive income (loss), before tax	2,114	223	7,265	461
Tax Effect
Net unrealized gain (loss)	(498)	(53)	(1,742)	(107)
Other reclassifications included in other revenue	0	1	0	1
Amortization of amounts previously recorded upon transfer to held to maturity from available for sale	0	(1)	0	(4)
Other	0	0	0	0
Other comprehensive income (loss)	(498)	(53)	(1,742)	(110)
Net of Tax
Net unrealized gain (loss)	1,615	165	5,522	338
Other reclassifications included in other revenue	0	(2)	0	(3)
Amortization of amounts previously recorded upon transfer from available for sale	0	7	0	16
Other	1	0	1	0
Other comprehensive income (loss), net of tax	$ 1,616	$ 170	$ 5,523	$ 351