Investment Securities (Gross Unrealized Loss and Fair Value of Securities Available for Sale Without an Allowance for Credit Losses) (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months, unrealized loss	$ (403)	$ (2,616)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	9,131	28,467
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(3,542)	(1,973)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	30,214	13,111
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(3,945)	(4,589)
Debt securities, available-for-sale, unrealized loss position, fair value	39,345	41,578
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	(55)	(601)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	1,316	5,868
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(665)	(235)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	5,995	2,208
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(720)	(836)
Debt securities, available-for-sale, unrealized loss position, fair value	7,311	8,076
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	(302)	(1,744)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	6,475	19,036
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(2,538)	(1,560)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	20,353	8,971
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(2,840)	(3,304)
Debt securities, available-for-sale, unrealized loss position, fair value	26,828	28,007
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	(6)	(6)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	93	112
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(3)	(2)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	30	17
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(9)	(8)
Debt securities, available-for-sale, unrealized loss position, fair value	123	129
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	(20)	(125)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	406	1,283
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(128)	(45)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	1,244	372
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(148)	(170)
Debt securities, available-for-sale, unrealized loss position, fair value	1,650	1,655
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	(8)	(44)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	86	750
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(46)	(18)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	756	394
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(54)	(62)
Debt securities, available-for-sale, unrealized loss position, fair value	842	1,144
Asset-backed
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	253
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(1)	(1)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	11	5
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(3)	(1)
Debt securities, available-for-sale, unrealized loss position, fair value	264	5
Other
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months, unrealized loss	(10)	(96)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	502	1,418
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(161)	(112)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	1,825	1,144
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(171)	(208)
Debt securities, available-for-sale, unrealized loss position, fair value	$ 2,327	$ 2,562