Securities - Schedule of Available for Sale Securities in an Unrealized Loss Position (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Held-to-maturity securities:
Temporarily impaired securities, fair value, less than 12 months	$ 5,497	$ 2,055
Temporarily impaired securities, gross unrealized losses, less than 12 months	17	79
Temporarily impaired securities, fair value, 12 months or longer	26,804	41,416
Temporarily impaired securities, gross unrealized losses, 12 months or longer	3,949	5,970
Temporarily impaired securities, fair value	32,301	43,471
Temporarily impaired securities, gross unrealized losses	3,966	6,049
U.S. Treasury, agencies and corporations
Securities available for sale:
Fair value, less than 12 months	3,228	0
Gross unrealized losses, less than 12 months	3	0
Fair value, 12 months or longer	766	8,532
Gross unrealized losses, 12 months or longer	27	280
Fair Value	3,994	8,532
Gross Unrealized Losses	30	280
Agency residential collateralized mortgage obligations
Securities available for sale:
Fair value, less than 12 months	93	0
Gross unrealized losses, less than 12 months	0	0
Fair value, 12 months or longer	11,807	14,979
Gross unrealized losses, 12 months or longer	2,663	3,437
Fair Value	11,900	14,979
Gross Unrealized Losses	2,663	3,437
Held-to-maturity securities:
Fair value, less than 12 months	164	1,123
Gross unrealized losses, less than 12 months	2	30
Fair value, 12 months or longer	3,585	3,070
Gross unrealized losses, 12 months or longer	216	253
Fair Value	3,749	4,193
Gross Unrealized Losses	218	283
Agency residential mortgage-backed securities
Securities available for sale:
Fair value, less than 12 months	2,012	24
Gross unrealized losses, less than 12 months	12	0
Fair value, 12 months or longer	3,369	3,562
Gross unrealized losses, 12 months or longer	498	600
Fair Value	5,381	3,586
Gross Unrealized Losses	510	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	143	152
Gross unrealized losses, 12 months or longer	11	13
Fair Value	143	152
Gross Unrealized Losses	11	13
Agency commercial mortgage-backed securities
Securities available for sale:
Fair value, less than 12 months	0	891
Gross unrealized losses, less than 12 months	0	49
Fair value, 12 months or longer	4,583	8,201
Gross unrealized losses, 12 months or longer	368	1,154
Fair Value	4,583	9,092
Gross Unrealized Losses	368	1,203
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	2,162	2,199
Gross unrealized losses, 12 months or longer	153	204
Fair Value	2,162	2,199
Gross Unrealized Losses	153	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	381	709
Gross unrealized losses, 12 months or longer	13	29
Fair Value	381	709
Gross Unrealized Losses	13	29
Other securities
Held-to-maturity securities:
Fair value, less than 12 months	0	17
Gross unrealized losses, less than 12 months	0	0
Fair value, 12 months or longer	8	12
Gross unrealized losses, 12 months or longer	0	0
Fair Value	8	29
Gross Unrealized Losses	$ 0	$ 0

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