DERIVATIVES - Fair Value Hedges (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Gain (loss) on fair value hedges
Gain (loss) under mark-to-market approach	$ 70	$ 93
Gain (loss) under amortization approach	32	7
Excluded component of fair value hedges | Excluded component of fair value hedges
Gain (loss) on fair value hedges
Other comprehensive income (loss), pretax	(10)	(10)	$ (12)	$ (14)
Other revenue
Gain (loss) on fair value hedges
Gain (loss) on the hedging derivatives included in assessment of the effectiveness of fair value hedges	359	(288)	1,664	673
Gain (loss) on the hedged item in designated and qualifying fair value hedges	(359)	288	(1,664)	(673)
Net gain (loss) on the hedging derivatives excluded from assessment of the effectiveness of fair value hedges	153	109	323	234
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	(128)	19	(1,168)	(473)
Gain (loss) on the hedged item in designated and qualifying fair value hedges	110	(21)	1,178	460
Net gain (loss) on the hedging derivatives excluded from assessment of the effectiveness of fair value hedges	0	0	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	0	0
Gain (loss) on the hedged item in designated and qualifying fair value hedges	0	0	0	0
Net gain (loss) on the hedging derivatives excluded from assessment of the effectiveness of fair value hedges	0	0	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	(128)	19	(1,168)	(473)
Gain (loss) on the hedged item in designated and qualifying fair value hedges	110	(21)	1,178	460
Net gain (loss) on the hedging derivatives excluded from assessment of the effectiveness of fair value hedges	0	0	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	350	(577)	424	709
Gain (loss) on the hedged item in designated and qualifying fair value hedges	(350)	577	(424)	(709)
Net gain (loss) on the hedging derivatives excluded from assessment of the effectiveness of fair value hedges	51	9	54	33
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	0	0
Gain (loss) on the hedged item in designated and qualifying fair value hedges	0	0	0	0
Net gain (loss) on the hedging derivatives excluded from assessment of the effectiveness of fair value hedges	0	0	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	9	289	1,240	(36)
Gain (loss) on the hedged item in designated and qualifying fair value hedges	(9)	(289)	(1,240)	36
Net gain (loss) on the hedging derivatives excluded from assessment of the effectiveness of fair value hedges	102	100	269	201
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	0	0
Gain (loss) on the hedged item in designated and qualifying fair value hedges	0	0	0	0
Net gain (loss) on the hedging derivatives excluded from assessment of the effectiveness of fair value hedges	$ 0	$ 0	$ 0	$ 0