GOODWILL AND INTANGIBLE ASSETS - Changes in Goodwill by Segment (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Goodwill
Balance of goodwill at beginning of period	$ 21,299	$ 20,098	$ 19,691	$ 21,299
Foreign exchange translation		(782)	407	(200)
Divestitures		(16)		(873)
Impairment of goodwill	(535)	0	0	(535)
Balance of goodwill at end of period		19,300	20,098	19,691
Goodwill impairment, after-tax	489
All Other
Goodwill
Balance of goodwill at beginning of period	2,367	1,108	964	2,367
Foreign exchange translation		(206)	144	5
Divestitures		0		(873)
Impairment of goodwill				(535)
Balance of goodwill at end of period		902	1,108	964
Services | Operating Segments
Goodwill
Balance of goodwill at beginning of period	2,105	2,214	2,167	2,105
Foreign exchange translation		(162)	47	62
Divestitures		0		0
Impairment of goodwill				0
Balance of goodwill at end of period		2,052	2,214	2,167
Markets
Goodwill
Goodwill transferred to (from)			537
Markets | Operating Segments
Goodwill
Balance of goodwill at beginning of period	6,078	5,870	5,785	6,078
Foreign exchange translation		(196)	85	(293)
Divestitures		0		0
Impairment of goodwill				0
Balance of goodwill at end of period		5,674	5,870	5,785
Banking
Goodwill
Goodwill transferred to (from)			(537)
Banking | Operating Segments
Goodwill
Balance of goodwill at beginning of period	1,032	1,039	1,034	1,032
Foreign exchange translation		(37)	5	2
Divestitures		0		0
Impairment of goodwill				0
Balance of goodwill at end of period		1,002	1,039	1,034
USPB | Operating Segments
Goodwill
Balance of goodwill at beginning of period	5,223	5,398	5,273	5,223
Foreign exchange translation		(179)	125	50
Divestitures		0		0
Impairment of goodwill				0
Balance of goodwill at end of period		5,219	5,398	5,273
Wealth | Operating Segments
Goodwill
Balance of goodwill at beginning of period	$ 4,494	4,469	4,468	4,494
Foreign exchange translation		(2)	1	(26)
Divestitures		(16)		0
Impairment of goodwill				0
Balance of goodwill at end of period		$ 4,451	$ 4,469	$ 4,468