AFS and HTM Debt Securities, Gross Unrealized Losses and Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Available-for-sale debt securities:
Less than 12 months, Gross unrealized losses, available-for-sale	$ (6,952)	$ (569)
Less than 12 months, Fair value, available-for-sale	85,977	71,006
12 months or more, Gross unrealized losses, available-for-sale	(2,225)	(285)
12 months or more, Fair value, available-for-sale	22,035	12,405
Total, Gross unrealized losses, available-for-sale	(9,177)	(854)
Total Fair value, available for sale	108,012	83,411
Securities of U.S. Treasury and federal agencies [Member]
Available-for-sale debt securities:
Less than 12 months, Gross unrealized losses, available-for-sale	(1,157)	(192)
Less than 12 months, Fair value, available-for-sale	27,415	24,418
12 months or more, Gross unrealized losses, available-for-sale	(1,218)	0
12 months or more, Fair value, available-for-sale	15,567	0
Total, Gross unrealized losses, available-for-sale	(2,375)	(192)
Total Fair value, available for sale	42,982	24,418
Securities of U.S. states and political subdivisions [Member]
Available-for-sale debt securities:
Less than 12 months, Gross unrealized losses, available-for-sale	(313)	(36)
Less than 12 months, Fair value, available-for-sale	4,015	2,308
12 months or more, Gross unrealized losses, available-for-sale	(256)	(15)
12 months or more, Fair value, available-for-sale	1,147	532
Total, Gross unrealized losses, available-for-sale	(569)	(51)
Total Fair value, available for sale	5,162	2,840
Federal agency mortgage-backed securities [Member]
Available-for-sale debt securities:
Less than 12 months, Gross unrealized losses, available-for-sale	(5,262)	(334)
Less than 12 months, Fair value, available-for-sale	46,912	40,695
12 months or more, Gross unrealized losses, available-for-sale	(673)	(248)
12 months or more, Fair value, available-for-sale	3,311	9,464
Total, Gross unrealized losses, available-for-sale	(5,935)	(582)
Total Fair value, available for sale	50,223	50,159
Non-agency mortgage-backed securities [Member]
Available-for-sale debt securities:
Less than 12 months, Gross unrealized losses, available-for-sale	(78)	(4)
Less than 12 months, Fair value, available-for-sale	2,343	1,966
12 months or more, Gross unrealized losses, available-for-sale	(43)	(11)
12 months or more, Fair value, available-for-sale	1,059	543
Total, Gross unrealized losses, available-for-sale	(121)	(15)
Total Fair value, available for sale	3,402	2,509
Collateralized loan obligations [Member]
Available-for-sale debt securities:
Less than 12 months, Gross unrealized losses, available-for-sale	(117)	(3)
Less than 12 months, Fair value, available-for-sale	3,659	1,619
12 months or more, Gross unrealized losses, available-for-sale	(19)	(4)
12 months or more, Fair value, available-for-sale	475	1,242
Total, Gross unrealized losses, available-for-sale	(136)	(7)
Total Fair value, available for sale	4,134	2,861
Other debt securities [Member]
Available-for-sale debt securities:
Less than 12 months, Gross unrealized losses, available-for-sale	(25)	0
Less than 12 months, Fair value, available-for-sale	1,633	0
12 months or more, Gross unrealized losses, available-for-sale	(16)	(7)
12 months or more, Fair value, available-for-sale	476	624
Total, Gross unrealized losses, available-for-sale	(41)	(7)
Total Fair value, available for sale	$ 2,109	$ 624