OPERATING SEGMENTS - Operations by Segment (Details) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) segment	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment				5
Segment Reporting Information [Line Items]
Net interest income		$ 13,362	$ 13,828	$ 40,362	$ 41,076
Non-interest revenue		6,953	6,311	21,196	19,946
Total revenues, net of interest expense		20,315	20,139	61,558	61,022
Provisions for credit losses and for benefits and claims	[1]	2,675	1,840	7,516	5,639
Provision (benefits) for income taxes		1,116	1,203	3,299	3,824
Income (loss) from continuing operations		3,274	3,585	9,945	11,189
Identifiable assets		2,430,663		2,430,663		$ 2,411,834
Average loans		687,000	662,000	682,000	657,000
Average deposits		1,311,000	1,315,000	1,316,000	1,339,000
Operating Segments
Segment Reporting Information [Line Items]
Income (loss) from continuing operations		3,319	3,371	10,116	10,419
Operating Segments | Services
Segment Reporting Information [Line Items]
Net interest income		3,435	3,440	9,977	9,809
Non-interest revenue		1,593	1,196	4,497	3,776
Total revenues, net of interest expense		5,028	4,636	14,474	13,585
Provisions for credit losses and for benefits and claims		127	95	164	304
Provision (benefits) for income taxes		630	666	1,626	1,952
Income (loss) from continuing operations		1,683	1,355	4,696	3,894
Identifiable assets		608,000		608,000		586,000
Average loans		87,000	83,000	84,000	81,000
Average deposits		825,000	797,000	812,000	814,000
Operating Segments | Markets
Segment Reporting Information [Line Items]
Net interest income		1,405	1,695	5,149	5,246
Non-interest revenue		3,412	3,053	10,111	10,037
Total revenues, net of interest expense		4,817	4,748	15,260	15,283
Provisions for credit losses and for benefits and claims		141	162	329	229
Provision (benefits) for income taxes		248	211	924	1,166
Income (loss) from continuing operations		1,089	1,065	3,979	4,066
Identifiable assets		1,002,000		1,002,000		1,008,000
Average loans		119,000	108,000	119,000	109,000
Average deposits		19,000	23,000	23,000	23,000
Operating Segments | Banking
Segment Reporting Information [Line Items]
Net interest income		527	555	1,636	1,610
Non-interest revenue		1,070	818	3,324	2,127
Total revenues, net of interest expense		1,597	1,373	4,960	3,737
Provisions for credit losses and for benefits and claims		177	(56)	16	(327)
Provision (benefits) for income taxes		68	47	346	83
Income (loss) from continuing operations		236	157	1,172	265
Identifiable assets		151,000		151,000		148,000
Average loans		88,000	89,000	89,000	92,000
Average deposits		1,000	1,000	1,000	1,000
Operating Segments | USPB
Segment Reporting Information [Line Items]
Net interest income		5,293	5,175	15,622	14,912
Non-interest revenue		(248)	(258)	(480)	(665)
Total revenues, net of interest expense		5,045	4,917	15,142	14,247
Provisions for credit losses and for benefits and claims		1,909	1,459	6,428	4,633
Provision (benefits) for income taxes		157	221	306	487
Income (loss) from continuing operations		522	756	990	1,619
Identifiable assets		245,000		245,000		242,000
Average loans		210,000	196,000	207,000	189,000
Average deposits		85,000	110,000	93,000	111,000
Operating Segments | Wealth
Segment Reporting Information [Line Items]
Net interest income		1,233	1,164	3,261	3,371
Non-interest revenue		769	667	2,248	1,986
Total revenues, net of interest expense		2,002	1,831	5,509	5,357
Provisions for credit losses and for benefits and claims		33	(2)	(146)	(7)
Provision (benefits) for income taxes		85	32	202	104
Income (loss) from continuing operations		283	132	668	398
Identifiable assets		230,000		230,000		229,000
Average loans		150,000	151,000	150,000	150,000
Average deposits		316,000	305,000	316,000	311,000
All Other
Segment Reporting Information [Line Items]
Net interest income		1,469	1,799	4,717	6,128
Non-interest revenue		356	439	1,474	1,277
Total revenues, net of interest expense		1,825	2,238	6,191	7,405
Provisions for credit losses and for benefits and claims		289	199	718	844
Provision (benefits) for income taxes		(52)	(59)	(29)	(377)
Income (loss) from continuing operations		(494)	(94)	(1,389)	177
Identifiable assets		195,000		195,000		$ 199,000
Average loans		33,000	35,000	33,000	36,000
Average deposits		65,000	79,000	71,000	79,000
Reconciling Items
Segment Reporting Information [Line Items]
Net interest income		0	0	0	0
Non-interest revenue		1	396	22	1,408
Total revenues, net of interest expense		1	396	22	1,408
Provisions for credit losses and for benefits and claims		(1)	(17)	7	(37)
Provision (benefits) for income taxes		(20)	85	(76)	409
Income (loss) from continuing operations		$ (45)	$ 214	$ (171)	$ 770

[1] In accordance with ASC 326, which requires the provision for credit losses on AFS debt securities to be included in revenue. The Total provisions for credit losses and for benefits and claims excludes the provision for credit losses on AFS debt securities, which is disclosed separately above.