SUBSIDIARY GURANTEES - Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and due from banks	$ 276,532	$ 260,932	$ 342,025	$ 262,033
Securities borrowed and purchased under resale agreements	274,062	345,700
Trading account assets	442,747	411,756
Other assets	102,206	95,963
Total assets	2,352,945	2,411,834	2,417,000
Securities loaned and sold under agreements to repurchase	254,755	278,107
Trading account liabilities	133,846	155,345
Short-term borrowings	48,505	37,457
Long-term debt	287,300	286,619
Other liabilities, plus allowances	68,114	75,835
Stockholders’ equity	209,366	206,251	201,838
Total liabilities and equity	2,352,945	2,411,834
Parent Company
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and due from banks	4,014	3,011	$ 3,015	$ 3,517
Trading account assets	(164)	113
Advances to subsidiaries	150,790	150,845
Other assets	75,400	56,900
Total assets	395,451	387,514
Trading account liabilities	(159)	34
Long-term debt	164,024	162,309
Stockholders’ equity	208,598	205,453
Total liabilities and equity	395,451	387,514
Parent Company | Subsidiary Holding Company
Condensed Balance Sheet Statements, Captions [Line Items]
Investments in subsidiaries	179,253	172,125
Advances from subsidiaries	10,948	8,677
Parent Company | Non-Bank Subsidiaries
Condensed Balance Sheet Statements, Captions [Line Items]
Investments in subsidiaries	46,549	46,870
Advances from subsidiaries	9,026	8,047
Parent Company | Reportable legal entities
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and due from banks	4,014	3,011
Securities borrowed and purchased under resale agreements	0	0
Trading account assets	203	461
Other assets	14,642	14,202
Securities loaned and sold under agreements to repurchase	0	0
Trading account liabilities	69	300
Short-term borrowings	0	0
Long-term debt	164,024	162,309
Advances from subsidiaries	19,974	16,724
Other liabilities, plus allowances	2,786	2,728
Stockholders’ equity	208,598	205,453
CGMHI | Reportable legal entities
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and due from banks	19,464	23,756
Securities borrowed and purchased under resale agreements	215,995	283,174
Trading account assets	294,396	273,379
Advances to subsidiaries	0	0
Other assets	158,080	167,609
Total assets	687,935	747,918
Securities loaned and sold under agreements to repurchase	268,178	309,862
Trading account liabilities	89,146	111,233
Short-term borrowings	29,410	20,481
Long-term debt	184,516	184,083
Advances from subsidiaries	0	0
Other liabilities, plus allowances	80,486	85,079
Stockholders’ equity	36,199	37,180
Total liabilities and equity	687,935	747,918
CGMHI | Reportable legal entities | Subsidiary Holding Company
Condensed Balance Sheet Statements, Captions [Line Items]
Investments in subsidiaries	0	0
CGMHI | Reportable legal entities | Non-Bank Subsidiaries
Condensed Balance Sheet Statements, Captions [Line Items]
Investments in subsidiaries	$ 0	$ 0