Investment Securities (Gross Unrealized Loss and Fair Value of Securities Available for Sale Without an Allowance for Credit Losses) (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months, unrealized loss	$ (2,814)	$ (790)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	44,466	80,895
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(399)	(26)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	3,705	2,211
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(3,213)	(816)
Debt securities, available-for-sale, unrealized loss position, fair value	48,171	83,106
U.S. Treasury and government agencies
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months, unrealized loss	(729)	(370)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	10,450	32,600
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(120)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	1,239
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(849)	(370)
Debt securities, available-for-sale, unrealized loss position, fair value	11,689	32,600
Residential mortgage-backed | Mortgage-backed Securities Agency
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months, unrealized loss	(1,811)	(369)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	28,806	41,521
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(263)	(20)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	2,135	1,489
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(2,074)	(389)
Debt securities, available-for-sale, unrealized loss position, fair value	30,941	43,010
Residential mortgage-backed | Mortgage-backed Securities Non-agency
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months, unrealized loss	(2)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	101
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(2)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	19
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(4)
Debt securities, available-for-sale, unrealized loss position, fair value	120
Commercial mortgage-backed | Mortgage-backed Securities Agency
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months, unrealized loss	(88)	(5)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	1,720	451
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(6)	(1)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	136	60
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(94)	(6)
Debt securities, available-for-sale, unrealized loss position, fair value	1,856	511
Commercial mortgage-backed | Mortgage-backed Securities Non-agency
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months, unrealized loss	(31)	(4)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	1,078	1,453
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(3)	(3)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	140	474
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(34)	(7)
Debt securities, available-for-sale, unrealized loss position, fair value	1,218	1,927
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months, unrealized loss		(29)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value		3,465
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss		(2)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value		188
Debt securities, available-for-sale, unrealized loss position, accumulated loss		(31)
Debt securities, available-for-sale, unrealized loss position, fair value		3,653
Other
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months, unrealized loss	(153)	(13)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	2,311	1,405
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(5)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	36
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(158)	(13)
Debt securities, available-for-sale, unrealized loss position, fair value	$ 2,347	$ 1,405