Investment Securities - Schedule of Unrealized Losses (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Investment securities available for sale
Investment securities available for sale, less than 12 months, fair value	$ 8,240	$ 3,501
Investment securities available for sale, less than 12 months, unrealized losses	(49)	(276)
Investment securities available for sale, 12 months or more, fair value	7,766	5,347
Investment securities available for sale, 12 months or more, unrealized losses	(1,126)	(697)
Investment securities available for sale, fair value	16,006	8,848
Investment securities available for sale, unrealized losses	(1,175)	(973)
U.S. Treasury
Investment securities available for sale
Investment securities available for sale, less than 12 months, fair value	6,322	403
Investment securities available for sale, less than 12 months, unrealized losses	(6)	(27)
Investment securities available for sale, 12 months or more, fair value	1,887	1,495
Investment securities available for sale, 12 months or more, unrealized losses	(112)	(110)
Investment securities available for sale, fair value	8,209	1,898
Investment securities available for sale, unrealized losses	(118)	(137)
Government agency
Investment securities available for sale
Investment securities available for sale, less than 12 months, fair value	26	65
Investment securities available for sale, less than 12 months, unrealized losses	0	(1)
Investment securities available for sale, 12 months or more, fair value	103	62
Investment securities available for sale, 12 months or more, unrealized losses	(3)	(1)
Investment securities available for sale, fair value	129	127
Investment securities available for sale, unrealized losses	(3)	(2)
Residential mortgage-backed securities
Investment securities available for sale
Investment securities available for sale, less than 12 months, fair value	1,465	1,698
Investment securities available for sale, less than 12 months, unrealized losses	(28)	(165)
Investment securities available for sale, 12 months or more, fair value	4,030	3,001
Investment securities available for sale, 12 months or more, unrealized losses	(724)	(465)
Investment securities available for sale, fair value	5,495	4,699
Investment securities available for sale, unrealized losses	(752)	(630)
Commercial mortgage-backed securities
Investment securities available for sale
Investment securities available for sale, less than 12 months, fair value	331	836
Investment securities available for sale, less than 12 months, unrealized losses	(3)	(53)
Investment securities available for sale, 12 months or more, fair value	1,364	752
Investment securities available for sale, 12 months or more, unrealized losses	(242)	(117)
Investment securities available for sale, fair value	1,695	1,588
Investment securities available for sale, unrealized losses	(245)	(170)
Corporate Bonds
Investment securities available for sale
Investment securities available for sale, less than 12 months, fair value	96	499
Investment securities available for sale, less than 12 months, unrealized losses	(12)	(30)
Investment securities available for sale, 12 months or more, fair value	382	37
Investment securities available for sale, 12 months or more, unrealized losses	(45)	(4)
Investment securities available for sale, fair value	478	536
Investment securities available for sale, unrealized losses	$ (57)	$ (34)

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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