Investment Securities - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Debt securities, available-for-sale, transferred security, at carrying value		$ 23,560,000,000	$ 1,250,000,000
Debt securities, available-for-sale, unrealized gain (loss)		1,260,000,000	12,000,000
Gains (losses) from sales of available-for-sale securities, net	$ 294,000,000	2,000,000	(57,000,000)
Debt securities, AFS, allowance	0	2,000,000	2,000,000
Asset Pledged as Collateral
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Pledged securities not separately reported	71,300,000,000	70,520,000,000
ABS and municipal bonds
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Securities sold	4,920,000,000	4,590,000,000	12,820,000,000
Gains (losses) from sales of available-for-sale securities, net	$ 294,000,000	$ 2,000,000	$ (57,000,000)
Minimum
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Debt securities, available-for-sale, securities transferred, security term		1 year
Maximum
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Debt securities, available-for-sale, securities transferred, security term		37 years