Investment Securities - Gross Unrealized Losses and Fair Values of Investments in Continuous Unrealized Loss Positions (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
AFS securities, Fair Value
Less than 12 months	$ 115,791	$ 4,534
12 months or more	3,655	239
Total	119,446	4,773
AFS securities, Unrealized Losses
Less than 12 months	2,564	23
12 months or more	156	3
Total	2,720	26
U.S. Treasury
AFS securities, Fair Value
Less than 12 months	8,412	17
12 months or more	582	0
Total	8,994	17
AFS securities, Unrealized Losses
Less than 12 months	88	0
12 months or more	18	0
Total	106	0
GSE
AFS securities, Fair Value
Less than 12 months	104
12 months or more	0
Total	104
AFS securities, Unrealized Losses
Less than 12 months	2
12 months or more	0
Total	2
Agency MBS | Agency MBS - residential
AFS securities, Fair Value
Less than 12 months	101,262	4,028
12 months or more	2,638	203
Total	103,900	4,231
AFS securities, Unrealized Losses
Less than 12 months	2,377	21
12 months or more	123	2
Total	2,500	23
Agency MBS | Commercial Mortgage Backed Securities
AFS securities, Fair Value
Less than 12 months	1,749	463
12 months or more	413	4
Total	2,162	467
AFS securities, Unrealized Losses
Less than 12 months	50	2
12 months or more	14	0
Total	64	2
States and political subdivisions
AFS securities, Fair Value
Less than 12 months	0	20
12 months or more	22	32
Total	22	52
AFS securities, Unrealized Losses
Less than 12 months	0	0
12 months or more	1	1
Total	1	1
Non-agency MBS
AFS securities, Fair Value
Less than 12 months	4,258
12 months or more	0
Total	4,258
AFS securities, Unrealized Losses
Less than 12 months	47
12 months or more	0
Total	47
Other
AFS securities, Fair Value
Less than 12 months	6	6
12 months or more	0	0
Total	6	6
AFS securities, Unrealized Losses
Less than 12 months	0	0
12 months or more	0	0
Total	$ 0	$ 0