Derivatives - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Derivative Instruments, Gain (Loss) [Line Items]
Collateral cash payables	$ 296		$ 296		$ 489
Total trading revenues	38	$ 19	113	$ 68
Hedged amount of foreign currency denominated loans	11		11		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	19		19		12
Net fair value of derivative liabilities with adjustable posting thresholds	114		114		188
Collateral received	95		95		95
Securities posted collateral	48		48		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	19		19		12
Net fair value of derivative liabilities with adjustable posting thresholds	114		114		188
Collateral received	95		95		95
Securities posted collateral	48		48		83
Credit Risk Contract
Derivative Instruments, Gain (Loss) [Line Items]
Derivative asset, notional amount	326		326		351
Derivative liability, notional amount	918		918		874
Visa Class B Shares
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liabilities related to sale	32		32		23
Derivative valuation adjustment	15		15		15
Counterparties
Derivative Instruments, Gain (Loss) [Line Items]
Collateral cash receivables	323		323		406
Collateral cash payables	$ 28		$ 28		$ 33