DERIVATIVES - Fair Value Hedges (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Gain (loss) on fair value hedges
Gain (loss) under mark-to-market approach	$ 170	$ 93
Gain (loss) under amortization approach	32	5
Excluded component of fair value hedges | Excluded component of fair value hedges
Gain (loss) on fair value hedges
Other comprehensive income (loss), pretax	10	(4)
Other revenue
Gain (loss) on fair value hedges
Gain (loss) on the hedging derivatives included in assessment of the effectiveness of fair value hedges	(265)	1,449
Gain (loss) on the hedged item in designated and qualifying fair value hedges	265	(1,449)
Net gain (loss) on the hedging derivatives excluded from assessment of the effectiveness of fair value hedges	229	69
Net interest income
Gain (loss) on fair value hedges
Gain (loss) on the hedging derivatives included in assessment of the effectiveness of fair value hedges	(414)	(604)
Gain (loss) on the hedged item in designated and qualifying fair value hedges	419	620
Net gain (loss) on the hedging derivatives excluded from assessment of the effectiveness of fair value hedges	0	0
Interest rate contracts (gross) | Other revenue
Gain (loss) on fair value hedges
Gain (loss) on the hedging derivatives included in assessment of the effectiveness of fair value hedges	0	0
Gain (loss) on the hedged item in designated and qualifying fair value hedges	0	0
Net gain (loss) on the hedging derivatives excluded from assessment of the effectiveness of fair value hedges	0	0
Interest rate contracts (gross) | Net interest income
Gain (loss) on fair value hedges
Gain (loss) on the hedging derivatives included in assessment of the effectiveness of fair value hedges	(414)	(604)
Gain (loss) on the hedged item in designated and qualifying fair value hedges	419	620
Net gain (loss) on the hedging derivatives excluded from assessment of the effectiveness of fair value hedges	0	0
Foreign exchange contracts (gross) | Other revenue
Gain (loss) on fair value hedges
Gain (loss) on the hedging derivatives included in assessment of the effectiveness of fair value hedges	9	(71)
Gain (loss) on the hedged item in designated and qualifying fair value hedges	(9)	71
Net gain (loss) on the hedging derivatives excluded from assessment of the effectiveness of fair value hedges	27	(29)
Foreign exchange contracts (gross) | Net interest income
Gain (loss) on fair value hedges
Gain (loss) on the hedging derivatives included in assessment of the effectiveness of fair value hedges	0	0
Gain (loss) on the hedged item in designated and qualifying fair value hedges	0	0
Net gain (loss) on the hedging derivatives excluded from assessment of the effectiveness of fair value hedges	0	0
Commodity hedges | Other revenue
Gain (loss) on fair value hedges
Gain (loss) on the hedging derivatives included in assessment of the effectiveness of fair value hedges	(274)	1,520
Gain (loss) on the hedged item in designated and qualifying fair value hedges	274	(1,520)
Net gain (loss) on the hedging derivatives excluded from assessment of the effectiveness of fair value hedges	202	98
Commodity hedges | Net interest income
Gain (loss) on fair value hedges
Gain (loss) on the hedging derivatives included in assessment of the effectiveness of fair value hedges	0	0
Gain (loss) on the hedged item in designated and qualifying fair value hedges	0	0
Net gain (loss) on the hedging derivatives excluded from assessment of the effectiveness of fair value hedges	$ 0	$ 0