CONDENSED CONSOLIDATING FINANCIAL STATEMENTS - Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Millions	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020
Assets
Cash and due from banks	$ 26,502		$ 27,515
Cash and due from banks—intercompany	0		0
Deposits with banks, net of allowance	273,105		234,518
Deposits with banks—intercompany	0		0
Securities borrowed and purchased under resale agreements	349,214		327,288
Securities borrowed and purchased under resale agreements—intercompany	0		0
Trading account assets	358,260		331,945
Trading account assets—intercompany	0		0
Investments	508,016		512,822
Loans, net of unearned income	645,960		667,767
Loans, net of unearned income—intercompany	0		0
Allowance for credit losses on loans (ACLL)	(16,309)	$ (15,952)	(16,455)	$ (17,715)	$ (19,238)	$ (24,956)
Total loans, net	629,651		651,312
Advances to subsidiaries	0		0
Investments in subsidiaries	0		0
Other assets, net of allowance	236,316		206,013
Other assets—intercompany	0		0
Total assets	2,381,064		2,291,413
Liabilities and equity
Deposits	1,306,486		1,317,230
Deposits—intercompany	0		0
Securities loaned and sold under repurchase agreements	203,429		191,285
Securities loaned and sold under repurchase agreements—intercompany	0		0
Trading account liabilities	196,479		161,529
Trading account liabilities—intercompany	0		0
Short-term borrowings	47,368		27,973
Short-term borrowings—intercompany	0		0
Long-term debt	253,068		254,374
Long-term debt—intercompany	0		0
Advances from subsidiaries	0		0
Other liabilities	175,117		136,350
Other liabilities—intercompany	0		0
Stockholders’ equity	199,117		202,672	$ 201,610
Total liabilities and equity	2,381,064		2,291,413
Increase in other assets	132,809		125,879
Citigroup parent company
Liabilities and equity
Long-term debt	159,251		164,945
Citibank, N.A.
Liabilities and equity
Increase in other assets	35,800		30,500
Citibank, N.A. | Up to 30 days
Liabilities and equity
Placements with term of less than 30 days	26,000		19,500
Reportable legal entities | Citigroup parent company
Assets
Cash and due from banks	0		0
Cash and due from banks—intercompany	25		17
Deposits with banks, net of allowance	0		0
Deposits with banks—intercompany	3,000		3,500
Securities borrowed and purchased under resale agreements	0		0
Securities borrowed and purchased under resale agreements—intercompany	0		0
Trading account assets	150		248
Trading account assets—intercompany	155		1,215
Investments	1		1
Loans, net of unearned income	0		0
Loans, net of unearned income—intercompany	0		0
Allowance for credit losses on loans (ACLL)	0		0
Total loans, net	0		0
Advances to subsidiaries	138,514		142,144
Investments in subsidiaries	219,162		223,303
Other assets, net of allowance	10,066		10,589
Other assets—intercompany	3,647		2,737
Total assets	374,720		383,754
Liabilities and equity
Deposits	0		0
Deposits—intercompany	0		0
Securities loaned and sold under repurchase agreements	0		0
Securities loaned and sold under repurchase agreements—intercompany	0		0
Trading account liabilities	44		17
Trading account liabilities—intercompany	660		777
Short-term borrowings	0		0
Short-term borrowings—intercompany	0		0
Long-term debt	159,251		164,945
Long-term debt—intercompany	0		0
Advances from subsidiaries	13,714		13,469
Other liabilities	2,405		2,574
Other liabilities—intercompany	86		0
Stockholders’ equity	198,560		201,972
Total liabilities and equity	374,720		383,754
Reportable legal entities | CGMHI
Assets
Cash and due from banks	1,405		834
Cash and due from banks—intercompany	5,903		6,890
Deposits with banks, net of allowance	8,582		7,936
Deposits with banks—intercompany	11,110		11,005
Securities borrowed and purchased under resale agreements	284,357		269,608
Securities borrowed and purchased under resale agreements—intercompany	20,830		23,362
Trading account assets	203,977		189,841
Trading account assets—intercompany	3,188		1,438
Investments	230		224
Loans, net of unearned income	1,633		2,293
Loans, net of unearned income—intercompany	0		0
Allowance for credit losses on loans (ACLL)	0		0
Total loans, net	1,633		2,293
Advances to subsidiaries	0		0
Investments in subsidiaries	0		0
Other assets, net of allowance	90,233		69,312
Other assets—intercompany	84,026		60,567
Total assets	715,474		643,310
Liabilities and equity
Deposits	0		0
Deposits—intercompany	0		0
Securities loaned and sold under repurchase agreements	183,473		171,818
Securities loaned and sold under repurchase agreements—intercompany	65,458		62,197
Trading account liabilities	116,473		122,383
Trading account liabilities—intercompany	3,475		500
Short-term borrowings	20,483		13,425
Short-term borrowings—intercompany	25,335		17,230
Long-term debt	75,887		61,416
Long-term debt—intercompany	81,276		76,335
Advances from subsidiaries	0		0
Other liabilities	92,435		68,206
Other liabilities—intercompany	12,092		11,774
Stockholders’ equity	39,087		38,026
Total liabilities and equity	715,474		643,310
Reportable legal entities | Other Citigroup subsidiaries and eliminations
Assets
Cash and due from banks	25,097		26,681
Cash and due from banks—intercompany	(5,928)		(6,907)
Deposits with banks, net of allowance	264,523		226,582
Deposits with banks—intercompany	(14,110)		(14,505)
Securities borrowed and purchased under resale agreements	64,857		57,680
Securities borrowed and purchased under resale agreements—intercompany	(20,830)		(23,362)
Trading account assets	154,133		141,856
Trading account assets—intercompany	(3,343)		(2,653)
Investments	507,785		512,597
Loans, net of unearned income	644,327		665,474
Loans, net of unearned income—intercompany	0		0
Allowance for credit losses on loans (ACLL)	(16,309)		(16,455)
Total loans, net	628,018		649,019
Advances to subsidiaries	(138,514)		(142,144)
Investments in subsidiaries	0		0
Other assets, net of allowance	136,017		126,112
Other assets—intercompany	(87,673)		(63,304)
Total assets	1,510,032		1,487,652
Liabilities and equity
Deposits	1,306,486		1,317,230
Deposits—intercompany	0		0
Securities loaned and sold under repurchase agreements	19,956		19,467
Securities loaned and sold under repurchase agreements—intercompany	(65,458)		(62,197)
Trading account liabilities	79,962		39,129
Trading account liabilities—intercompany	(4,135)		(1,277)
Short-term borrowings	26,885		14,548
Short-term borrowings—intercompany	(25,335)		(17,230)
Long-term debt	17,930		28,013
Long-term debt—intercompany	(81,276)		(76,335)
Advances from subsidiaries	(13,714)		(13,469)
Other liabilities	80,277		65,570
Other liabilities—intercompany	(12,178)		(11,774)
Stockholders’ equity	180,632		185,977
Total liabilities and equity	1,510,032		1,487,652
Consolidating adjustments
Assets
Cash and due from banks	0		0
Cash and due from banks—intercompany	0		0
Deposits with banks, net of allowance	0		0
Deposits with banks—intercompany	0		0
Securities borrowed and purchased under resale agreements	0		0
Securities borrowed and purchased under resale agreements—intercompany	0		0
Trading account assets	0		0
Trading account assets—intercompany	0		0
Investments	0		0
Loans, net of unearned income	0		0
Loans, net of unearned income—intercompany	0		0
Allowance for credit losses on loans (ACLL)	0		0
Total loans, net	0		0
Advances to subsidiaries	0		0
Investments in subsidiaries	(219,162)		(223,303)
Other assets, net of allowance	0		0
Other assets—intercompany	0		0
Total assets	(219,162)		(223,303)
Liabilities and equity
Deposits	0		0
Deposits—intercompany	0		0
Securities loaned and sold under repurchase agreements	0		0
Securities loaned and sold under repurchase agreements—intercompany	0		0
Trading account liabilities	0		0
Trading account liabilities—intercompany	0		0
Short-term borrowings	0		0
Short-term borrowings—intercompany	0		0
Long-term debt	0		0
Long-term debt—intercompany	0		0
Advances from subsidiaries	0		0
Other liabilities	0		0
Other liabilities—intercompany	0		0
Stockholders’ equity	(219,162)		(223,303)
Total liabilities and equity	$ (219,162)		$ (223,303)