DERIVATIVES - Effect of Derivative Instruments on Net Income and Stockholders' Equity (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax net gains (losses) recognized in OCI	$ (21)	$ 613	$ 376	$ (114)
Interest Income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of pretax net gains (losses) from OCI into income statement	(193)	(276)	(591)	(711)
Noninterest Income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of pretax net gains (losses) from OCI into income statement	(4)	0	(5)	0
Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
Amount of pretax net gains (losses) from OCI into income statement	$ 0	$ 0	$ (1)	$ 0