Investment Securities - Narrative (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
	Jan. 01, 2023	Sep. 30, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Investment securities transferred from AFS to HTM		$ 44,100
Unrealized gains included in AOCI for investment securities transferred from AFS to HTM		$ 575
Debt Securities, Available-for-sale [Line Items]
Approximate percentage rated at least AA+			99.00%	99.00%
Investment securities, allowance for credit losses			$ 106	$ 152	$ 128
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Securities sold			$ 17
Obligations of U.S. states and municipalities | Accounting Standards Update 2022-01
Debt Securities, Available-for-sale [Line Items]
Amount of investment securities transferred from HTM to AFS	$ 7,100
Pre-tax unrealized losses recognized within AOCI for transfer of securities from HTM to AFS	$ 38