SUBSIDIARY GURANTEES - Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and due from banks	$ 260,932	$ 342,025	$ 262,033	$ 309,615
Securities borrowed and purchased under resale agreements	345,700	365,401
Trading account assets	411,756	334,114
Other assets	95,963	103,743
Total assets	2,411,834	2,416,676	2,291,000
Securities loaned and sold under agreements to repurchase	278,107	202,444
Trading account liabilities	155,345	170,647
Short-term borrowings	37,457	47,096
Long-term debt	286,619	271,606
Other liabilities, plus allowances	75,835	87,873
Stockholders’ equity	206,251	201,838	202,672
Total liabilities and equity	2,411,834	2,416,676
Parent Company
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and due from banks	3,011	3,015	$ 3,517	$ 4,516
Trading account assets	113	130
Advances to subsidiaries	150,845	146,843
Other assets	56,900	40,200
Total assets	387,514	384,968
Trading account liabilities	34	23
Long-term debt	162,309	166,257
Stockholders’ equity	205,453	201,189
Total liabilities and equity	387,514	384,968
Parent Company | Subsidiary Holding Company
Condensed Balance Sheet Statements, Captions [Line Items]
Investments in subsidiaries	172,125	172,721
Advances from subsidiaries	8,677	6,629
Parent Company | Non-Bank Subsidiaries
Condensed Balance Sheet Statements, Captions [Line Items]
Investments in subsidiaries	46,870	48,295
Advances from subsidiaries	8,047	7,933
Parent Company | Reportable legal entities
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and due from banks	3,011	3,015
Securities borrowed and purchased under resale agreements	0	0
Trading account assets	461	306
Other assets	14,202	13,788
Securities loaned and sold under agreements to repurchase	0	0
Trading account liabilities	300	604
Short-term borrowings	0	0
Long-term debt	162,309	166,257
Advances from subsidiaries	16,724	14,562
Other liabilities, plus allowances	2,728	2,356
Stockholders’ equity	205,453	201,189
CGMHI | Reportable legal entities
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and due from banks	23,756	27,122
Securities borrowed and purchased under resale agreements	283,174	306,273
Trading account assets	273,379	209,957
Advances to subsidiaries	0	0
Other assets	167,609	163,819
Total assets	747,918	707,171
Securities loaned and sold under agreements to repurchase	309,862	245,916
Trading account liabilities	111,233	115,929
Short-term borrowings	20,481	43,850
Long-term debt	184,083	172,068
Advances from subsidiaries	0	0
Other liabilities, plus allowances	85,079	90,570
Stockholders’ equity	37,180	38,838
Total liabilities and equity	747,918	707,171
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