INVESTMENT SECURITIES - Gains and Losses Related to Equity Securities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Investments, Debt and Equity Securities [Abstract]
Net gains (losses) recognized on equity securities during the period	$ 0	$ 51	$ 1	$ (119)
Less: Net gains (losses) recognized on equity securities sold during the period	0	47	0	(105)
Unrealized gains (losses) recognized on equity securities still held at the end of the period	$ 0	$ 4	$ 1	$ (14)