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, 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	$ (72)	$ (2,616)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	4,087	28,467
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(4,327)	(1,973)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	35,077	13,111
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(4,399)	(4,589)
Debt securities, available-for-sale, unrealized loss position, fair value	39,164	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	(9)	(601)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	898	5,868
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(751)	(235)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	5,983	2,208
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(760)	(836)
Debt securities, available-for-sale, unrealized loss position, fair value	6,881	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	(51)	(1,744)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	2,309	19,036
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(3,167)	(1,560)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	24,700	8,971
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(3,218)	(3,304)
Debt securities, available-for-sale, unrealized loss position, fair value	27,009	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	(1)	(6)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	46	112
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(6)	(2)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	67	17
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(7)	(8)
Debt securities, available-for-sale, unrealized loss position, fair value	113	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	(2)	(125)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	89	1,283
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(165)	(45)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	1,485	372
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(167)	(170)
Debt securities, available-for-sale, unrealized loss position, fair value	1,574	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		(44)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value		750
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(57)	(18)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	808	394
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(57)	(62)
Debt securities, available-for-sale, unrealized loss position, fair value	808	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	(3)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	502
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	12	5
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(4)	(1)
Debt securities, available-for-sale, unrealized loss position, fair value	514	5
Other
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months, unrealized loss	(6)	(96)
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months - fair value	243	1,418
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, unrealized loss	(180)	(112)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer - fair value	2,022	1,144
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(186)	(208)
Debt securities, available-for-sale, unrealized loss position, fair value	$ 2,265	$ 2,562