Investment Securities (Gross Unrealized Loss and Fair Value of Securities Available for Sale Without an Allowance for Credit Losses) (Details) - USD ($) $ in Millions	Sep. 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	$ (4,098)	$ (790)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	38,715	80,895
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(872)	(26)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	4,717	2,211
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(4,970)	(816)
Debt securities, available-for-sale, unrealized loss position, fair value	43,432	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	(817)	(370)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	9,462	32,600
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(67)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	404
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(884)	(370)
Debt securities, available-for-sale, unrealized loss position, fair value	9,866	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	(2,874)	(369)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	24,373	41,521
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(735)	(20)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	3,602	1,489
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(3,609)	(389)
Debt securities, available-for-sale, unrealized loss position, fair value	27,975	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	(3)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	71
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(1)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	17
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(4)
Debt securities, available-for-sale, unrealized loss position, fair value	88
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	(166)	(5)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	1,588	451
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(10)	(1)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	144	60
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(176)	(6)
Debt securities, available-for-sale, unrealized loss position, fair value	1,732	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	(42)	(4)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	945	1,453
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(7)	(3)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	236	474
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(49)	(7)
Debt securities, available-for-sale, unrealized loss position, fair value	1,181	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	(1)	(29)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	10	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	(1)	(31)
Debt securities, available-for-sale, unrealized loss position, fair value	10	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	(195)	(13)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	2,266	1,405
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(52)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	314
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(247)	(13)
Debt securities, available-for-sale, unrealized loss position, fair value	$ 2,580	$ 1,405