Securities - Schedule of Available for Sale Securities in an Unrealized Loss Position (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Held-to-maturity securities:
Temporarily impaired securities, fair value, less than 12 months	$ 3,738	$ 2,055
Temporarily impaired securities, gross unrealized losses, less than 12 months	83	79
Temporarily impaired securities, fair value, 12 months or longer	38,570	41,416
Temporarily impaired securities, gross unrealized losses, 12 months or longer	6,173	5,970
Temporarily impaired securities, fair value	42,308	43,471
Temporarily impaired securities, gross unrealized losses	6,256	6,049
U.S. Treasury, agencies and corporations
Securities available for sale:
Fair value, less than 12 months	1,556	0
Gross unrealized losses, less than 12 months	8	0
Fair value, 12 months or longer	6,505	8,532
Gross unrealized losses, 12 months or longer	130	280
Fair Value	8,061	8,532
Gross Unrealized Losses	138	280
Agency residential collateralized mortgage obligations
Securities available for sale:
Fair value, less than 12 months	198	0
Gross unrealized losses, less than 12 months	1	0
Fair value, 12 months or longer	14,051	14,979
Gross unrealized losses, 12 months or longer	3,558	3,437
Fair Value	14,249	14,979
Gross Unrealized Losses	3,559	3,437
Held-to-maturity securities:
Fair value, less than 12 months	491	1,123
Gross unrealized losses, less than 12 months	4	30
Fair value, 12 months or longer	3,800	3,070
Gross unrealized losses, 12 months or longer	352	253
Fair Value	4,291	4,193
Gross Unrealized Losses	356	283
Agency residential mortgage-backed securities
Securities available for sale:
Fair value, less than 12 months	632	24
Gross unrealized losses, less than 12 months	2	0
Fair value, 12 months or longer	3,343	3,562
Gross unrealized losses, 12 months or longer	635	600
Fair Value	3,975	3,586
Gross Unrealized Losses	637	600
Held-to-maturity securities:
Fair value, less than 12 months	0	0
Gross unrealized losses, less than 12 months	0	0
Fair value, 12 months or longer	140	152
Gross unrealized losses, 12 months or longer	17	13
Fair Value	140	152
Gross Unrealized Losses	17	13
Agency commercial mortgage-backed securities
Securities available for sale:
Fair value, less than 12 months	823	891
Gross unrealized losses, less than 12 months	68	49
Fair value, 12 months or longer	8,123	8,201
Gross unrealized losses, 12 months or longer	1,243	1,154
Fair Value	8,946	9,092
Gross Unrealized Losses	1,311	1,203
Held-to-maturity securities:
Fair value, less than 12 months	23	0
Gross unrealized losses, less than 12 months	0	0
Fair value, 12 months or longer	2,117	2,199
Gross unrealized losses, 12 months or longer	225	204
Fair Value	2,140	2,199
Gross Unrealized Losses	225	204
Asset-backed securities
Held-to-maturity securities:
Fair value, less than 12 months	0	0
Gross unrealized losses, less than 12 months	0	0
Fair value, 12 months or longer	481	709
Gross unrealized losses, 12 months or longer	12	29
Fair Value	481	709
Gross Unrealized Losses	12	29
Other securities
Held-to-maturity securities:
Fair value, less than 12 months	15	17
Gross unrealized losses, less than 12 months	0	0
Fair value, 12 months or longer	10	12
Gross unrealized losses, 12 months or longer	1	0
Fair Value	25	29
Gross Unrealized Losses	$ 1	$ 0

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