Investment Securities - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Jan. 31, 2024	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Summary of Investment Holdings [Line Items]
Accrued interest receivables on investment securities		$ 158		$ 158		$ 146
Transfer of available-for-sale securities to held-to-maturity	$ 12,600
OCI, available-for-sale debt securities transferred to held-to-maturity, pretax unrealized losses	$ 994
Impairment losses		5	$ 4	10	$ 4
Securities with a fair value, pledged as collateral		31,300		31,300		25,200
Unrealized losses		4,617		4,617		5,379
Total gains (losses) recognized in income from available-for-sale debt and other securities, trading debt securities and equity securities		3	7	13	11
Commercial Banking Revenue and Wealth and Asset Management Revenue
Summary of Investment Holdings [Line Items]
Total gains (losses) recognized in income from available-for-sale debt and other securities, trading debt securities and equity securities		0	$ (1)	2	$ 0
Available-for-sale debt securities transferred to held-to-maturity securities
Summary of Investment Holdings [Line Items]
AOCI offset, unamortized portion of unrealized losses on securities		930		930
Non-rated Securities
Summary of Investment Holdings [Line Items]
Unrealized losses		37		37		45
Other Debt Obligations [Member]
Summary of Investment Holdings [Line Items]
Securities gains (losses)		293		293		224
FRB, restricted stock holdings		499		499		496
DTCC, restricted stock holdings		$ 2		$ 2		$ 2