CONDENSED CONSOLIDATING FINANCIAL STATEMENTS - Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021
Assets
Cash and due from banks	$ 26,224	$ 30,577
Cash and due from banks—intercompany	0	0
Deposits with banks, net of allowance	302,735	311,448
Deposits with banks—intercompany	0	0
Securities borrowed and purchased under resale agreements	384,198	365,401
Securities borrowed and purchased under resale agreements—intercompany	0	0
Trading account assets	383,906	334,114
Trading account assets—intercompany	0	0
Investments, net of allowance	512,578	526,582
Loans, net of unearned income	651,995	657,221
Loans, net of unearned income—intercompany	0	0
Allowance for credit losses on loans (ACLL)	(17,169)	(16,974)	$ (15,393)	$ (16,455)
Total loans, net	634,826	640,247
Advances to subsidiaries	0	0
Other assets, net of allowance	210,646	208,307
Other assets—intercompany	0	0
Total assets	2,455,113	2,416,676
Liabilities and equity
Deposits	1,330,459	1,365,954
Deposits—intercompany	0	0
Securities loaned and sold under repurchase agreements	257,681	202,444
Securities loaned and sold under repurchase agreements—intercompany	0	0
Trading account liabilities	185,010	170,647
Trading account liabilities—intercompany	0	0
Short-term borrowings	40,187	47,096
Short-term borrowings—intercompany	0	0
Long-term debt	279,684	271,606
Long-term debt—intercompany	0	0
Other liabilities	153,073	157,091
Other liabilities—intercompany	0	0
Stockholders’ equity	209,019	201,838	$ 198,353
Total liabilities and equity	2,455,113	2,416,676
Increase in other assets	103,522	103,743
Subsidiary Holding Company
Assets
Investments in subsidiary bank holding company	0	0
Liabilities and equity
Advances from subsidiary bank holding company	0	0
Non-Bank Subsidiaries
Assets
Investments in subsidiary bank holding company	0	0
Liabilities and equity
Advances from subsidiary bank holding company	0	0
Citigroup parent company
Liabilities and equity
Long-term debt	166,826	166,257
Citibank, N.A.
Liabilities and equity
Increase in other assets	46,800	40,200
Citibank, N.A. | Up to 30 days
Liabilities and equity
Placements with term of less than 30 days	35,200	29,200
Reportable legal entities | Citigroup parent company
Assets
Cash and due from banks	0	0
Cash and due from banks—intercompany	33	15
Deposits with banks, net of allowance	0	0
Deposits with banks—intercompany	4,000	3,000
Securities borrowed and purchased under resale agreements	0	0
Securities borrowed and purchased under resale agreements—intercompany	0	0
Trading account assets	148	130
Trading account assets—intercompany	247	176
Investments, net of allowance	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	146,754	146,843
Other assets, net of allowance	11,493	10,441
Other assets—intercompany	4,577	3,346
Total assets	391,669	384,968
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	32	23
Trading account liabilities—intercompany	722	581
Short-term borrowings	0	0
Short-term borrowings—intercompany	0	0
Long-term debt	166,826	166,257
Long-term debt—intercompany	0	0
Other liabilities	2,627	2,321
Other liabilities—intercompany	104	35
Stockholders’ equity	208,295	201,189
Total liabilities and equity	391,669	384,968
Reportable legal entities | Citigroup parent company | Subsidiary Holding Company
Assets
Investments in subsidiary bank holding company	176,035	172,721
Liabilities and equity
Advances from subsidiary bank holding company	5,028	6,629
Reportable legal entities | Citigroup parent company | Non-Bank Subsidiaries
Assets
Investments in subsidiary bank holding company	48,381	48,295
Liabilities and equity
Advances from subsidiary bank holding company	8,035	7,933
Reportable legal entities | CGMHI
Assets
Cash and due from banks	739	955
Cash and due from banks—intercompany	5,846	7,448
Deposits with banks, net of allowance	7,107	7,902
Deposits with banks—intercompany	9,514	10,816
Securities borrowed and purchased under resale agreements	307,774	286,724
Securities borrowed and purchased under resale agreements—intercompany	20,355	19,549
Trading account assets	248,341	202,678
Trading account assets—intercompany	4,889	7,279
Investments, net of allowance	250	265
Loans, net of unearned income	1,884	1,749
Loans, net of unearned income—intercompany	111	337
Allowance for credit losses on loans (ACLL)	(14)	0
Total loans, net	1,981	2,086
Advances to subsidiaries	0	0
Other assets, net of allowance	67,102	66,753
Other assets—intercompany	97,995	94,716
Total assets	771,893	707,171
Liabilities and equity
Deposits	0	0
Deposits—intercompany	0	0
Securities loaned and sold under repurchase agreements	236,426	181,765
Securities loaned and sold under repurchase agreements—intercompany	62,675	64,151
Trading account liabilities	123,141	108,940
Trading account liabilities—intercompany	3,787	6,989
Short-term borrowings	17,079	20,382
Short-term borrowings—intercompany	15,390	23,468
Long-term debt	96,700	88,844
Long-term debt—intercompany	90,431	83,224
Other liabilities	75,199	75,040
Other liabilities—intercompany	12,090	15,530
Stockholders’ equity	38,975	38,838
Total liabilities and equity	771,893	707,171
Reportable legal entities | CGMHI | Subsidiary Holding Company
Assets
Investments in subsidiary bank holding company	0	0
Liabilities and equity
Advances from subsidiary bank holding company	0	0
Reportable legal entities | CGMHI | Non-Bank Subsidiaries
Assets
Investments in subsidiary bank holding company	0	0
Liabilities and equity
Advances from subsidiary bank holding company	0	0
Reportable legal entities | Other Citigroup subsidiaries and eliminations
Assets
Cash and due from banks	25,485	29,622
Cash and due from banks—intercompany	(5,879)	(7,463)
Deposits with banks, net of allowance	295,628	303,546
Deposits with banks—intercompany	(13,514)	(13,816)
Securities borrowed and purchased under resale agreements	76,424	78,677
Securities borrowed and purchased under resale agreements—intercompany	(20,355)	(19,549)
Trading account assets	135,417	131,306
Trading account assets—intercompany	(5,136)	(7,455)
Investments, net of allowance	512,327	526,316
Loans, net of unearned income	650,111	655,472
Loans, net of unearned income—intercompany	(111)	(337)
Allowance for credit losses on loans (ACLL)	(17,155)	(16,974)
Total loans, net	632,845	638,161
Advances to subsidiaries	(146,754)	(146,843)
Other assets, net of allowance	132,051	131,113
Other assets—intercompany	(102,572)	(98,062)
Total assets	1,515,967	1,545,553
Liabilities and equity
Deposits	1,330,459	1,365,954
Deposits—intercompany	0	0
Securities loaned and sold under repurchase agreements	21,255	20,679
Securities loaned and sold under repurchase agreements—intercompany	(62,675)	(64,151)
Trading account liabilities	61,837	61,684
Trading account liabilities—intercompany	(4,509)	(7,570)
Short-term borrowings	23,108	26,714
Short-term borrowings—intercompany	(15,390)	(23,468)
Long-term debt	16,158	16,505
Long-term debt—intercompany	(90,431)	(83,224)
Other liabilities	75,247	79,730
Other liabilities—intercompany	(12,194)	(15,565)
Stockholders’ equity	186,165	182,827
Total liabilities and equity	1,515,967	1,545,553
Reportable legal entities | Other Citigroup subsidiaries and eliminations | Subsidiary Holding Company
Assets
Investments in subsidiary bank holding company	0	0
Liabilities and equity
Advances from subsidiary bank holding company	(5,028)	(6,629)
Reportable legal entities | Other Citigroup subsidiaries and eliminations | Non-Bank Subsidiaries
Assets
Investments in subsidiary bank holding company	0	0
Liabilities and equity
Advances from subsidiary bank holding company	(8,035)	(7,933)
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, net of allowance	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
Other assets, net of allowance	0	0
Other assets—intercompany	0	0
Total assets	(224,416)	(221,016)
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
Other liabilities	0	0
Other liabilities—intercompany	0	0
Stockholders’ equity	(224,416)	(221,016)
Total liabilities and equity	(224,416)	(221,016)
Consolidating adjustments | Subsidiary Holding Company
Assets
Investments in subsidiary bank holding company	(176,035)	(172,721)
Liabilities and equity
Advances from subsidiary bank holding company	0	0
Consolidating adjustments | Non-Bank Subsidiaries
Assets
Investments in subsidiary bank holding company	(48,381)	(48,295)
Liabilities and equity
Advances from subsidiary bank holding company	$ 0	$ 0