Investment Securities - Gross Unrealized Losses and Fair Values of Investments in Continuous Unrealized Loss Positions (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
AFS securities, Fair Value
Less than 12 months	$ 3,011	$ 28,352
12 months or more	68,258	43,118
Total	71,269	71,470
AFS securities, Unrealized Losses
Less than 12 months	122	3,439
12 months or more	11,038	8,831
Total	11,160	12,270
U.S. Treasury
AFS securities, Fair Value
Less than 12 months	1,267	2,069
12 months or more	8,977	8,186
Total	10,244	10,255
AFS securities, Unrealized Losses
Less than 12 months	27	49
12 months or more	617	736
Total	644	785
GSE
AFS securities, Fair Value
Less than 12 months	112	180
12 months or more	175	114
Total	287	294
AFS securities, Unrealized Losses
Less than 12 months	5	14
12 months or more	26	22
Total	31	36
Agency MBS - residential
AFS securities, Fair Value
Less than 12 months	1,267	25,041
12 months or more	53,717	30,050
Total	54,984	55,091
AFS securities, Unrealized Losses
Less than 12 months	65	3,263
12 months or more	9,143	6,889
Total	9,208	10,152
Debt Securities, Held-to-Maturity, Fair Value
Less than 12 months	0	29,369
12 months or more	48,097	18,422
Total	48,097	47,791
Debt Securities, Held-To-Maturity, Unrealized Losses
Less than 12 months	0	5,613
12 months or more	8,835	4,309
Total	8,835	9,922
Agency MBS - commercial
AFS securities, Fair Value
Less than 12 months	318	790
12 months or more	2,066	1,631
Total	2,384	2,421
AFS securities, Unrealized Losses
Less than 12 months	24	92
12 months or more	450	371
Total	474	463
States and political subdivisions
AFS securities, Fair Value
Less than 12 months	42	251
12 months or more	210	20
Total	252	271
AFS securities, Unrealized Losses
Less than 12 months	1	21
12 months or more	16	3
Total	17	24
Non-agency MBS
AFS securities, Fair Value
Less than 12 months	0	0
12 months or more	3,098	3,117
Total	3,098	3,117
AFS securities, Unrealized Losses
Less than 12 months	0	0
12 months or more	786	810
Total	786	810
Other
AFS securities, Fair Value
Less than 12 months	5	21
12 months or more	15	0
Total	20	21
AFS securities, Unrealized Losses
Less than 12 months	0	0
12 months or more	0	0
Total	$ 0	$ 0