Derivatives - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Derivative Instruments, Gain (Loss) [Line Items]
Collateral cash payables	$ 553		$ 489
Total trading revenues	45	$ 27
Hedged amount of foreign currency denominated loans	22		17
Additional Derivative Agreements | Derivative Instruments With Adjustable Collateral Posting Thresholds
Derivative Instruments, Gain (Loss) [Line Items]
Net fair value of derivative assets with adjustable posting thresholds	5		12
Net fair value of derivative liabilities with adjustable posting thresholds	228		188
Collateral received	88		95
Securities posted collateral	99		83
Additional Derivative Agreements | Derivative Instruments With Accelerated Termination Provisions
Derivative Instruments, Gain (Loss) [Line Items]
Net fair value of derivative assets with adjustable posting thresholds	5		12
Net fair value of derivative liabilities with adjustable posting thresholds	228		188
Collateral received	88		95
Securities posted collateral	99		83
Credit Risk Contract
Derivative Instruments, Gain (Loss) [Line Items]
Derivative asset, notional amount	364		351
Derivative liability, notional amount	872		874
Visa Class B Shares
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liabilities related to sale	20		23
Derivative valuation adjustment			15
Counterparties
Derivative Instruments, Gain (Loss) [Line Items]
Collateral cash receivables	665		406
Collateral cash payables	$ 27		$ 33