CONDENSED CONSOLIDATING FINANCIAL STATEMENTS - Condensed Consolidating Statement of Cash Flows (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities of continuing operations		$ (13,544)	$ 23,198
Available-for-sale debt securities
Purchases of investments	[1]	(66,115)	(48,998)
Proceeds from sales of investments	[1]	57,084	45,960
Proceeds from maturities of investments	[1]	28,333	30,003
Held-to-maturity debt securities
Purchases of investments	[1]	(28,406)	(62,067)
Proceeds from maturities of investments	[1]	2,775	5,085
Change in loans		(9,643)	9,933
Proceeds from sales and securitizations of loans		676	323
Change in securities borrowed and purchased under agreements to resell		(18,122)	(20,360)
Changes in investments and advances—intercompany		0	0
Other investing activities		(1,105)	(813)
Net cash used in investing activities of continuing operations		(34,523)	(40,934)
Cash flows from financing activities of continuing operations
Dividends paid		(1,286)	(1,356)
Issuance of preferred stock		0	2,300
Redemption of preferred stock		0	(1,500)
Treasury stock acquired		(2,833)	(1,481)
Proceeds (repayments) from issuance of long-term debt, net		12,607	(6,916)
Proceeds (repayments) from issuance of long-term debt—intercompany, net		0	0
Change in deposits		34,816	20,304
Change in securities loaned and sold under agreements to repurchase		13,209	19,643
Change in short-term borrowings		2,171	2,573
Net change in short-term borrowings and other advances—intercompany		0	0
Capital contributions from (to) parent		0
Other financing activities		(330)	(312)
Net cash provided by financing activities of continuing operations		58,354	33,255
Effect of exchange rate changes on cash and due from banks		(233)	(452)
Change in cash, due from banks and deposits with banks		10,054	15,067
Cash, due from banks and deposits with banks at beginning of period		262,033	309,615
Cash, due from banks and deposits with banks at end of period		272,087	324,682
Cash and due from banks		27,768	26,204	$ 27,515
Deposits with banks, net of allowance		244,319	298,478	234,518
Cash, due from banks and deposits with banks at end of period		272,087	324,682	262,033
Supplemental disclosure of cash flow information for continuing operations
Cash paid (received) during the period for income taxes		631	950
Cash paid during the period for interest		2,782	1,389
Non-cash investing and financing activities
Decrease in net loans associated with significant disposals reclassified to HFS	[2],[3]	14,970	0
Decrease in goodwill associated with significant disposals reclassified to HFS	[2],[3]	715	0
Transfers to loans HFS (Other assets) from loans	[2],[3]	328	636
Decrease in deposits associated with significant disposals reclassified to HFS	[3]	18,334	0
Decrease in long-term debt associated with significant disposals reclassified to HFS	[3]	28	0
Reportable legal entities | Citigroup parent company
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities of continuing operations		(4,607)	(4,966)
Available-for-sale debt securities
Purchases of investments		0	0
Proceeds from sales of investments		0	0
Proceeds from maturities of investments		0	0
Held-to-maturity debt securities
Purchases of investments		0	0
Proceeds from maturities of investments		0	0
Change in loans		0	0
Proceeds from sales and securitizations of loans		0	0
Change in securities borrowed and purchased under agreements to resell		0	0
Changes in investments and advances—intercompany		(9,916)	1,887
Other investing activities		0	0
Net cash used in investing activities of continuing operations		(9,916)	1,887
Cash flows from financing activities of continuing operations
Dividends paid		(1,286)	(1,356)
Issuance of preferred stock			2,300
Redemption of preferred stock			(1,500)
Treasury stock acquired		(2,833)	(1,481)
Proceeds (repayments) from issuance of long-term debt, net		10,447	(1,039)
Proceeds (repayments) from issuance of long-term debt—intercompany, net		0	0
Change in deposits		0	0
Change in securities loaned and sold under agreements to repurchase		0	0
Change in short-term borrowings		0	0
Net change in short-term borrowings and other advances—intercompany		8,530	4,962
Capital contributions from (to) parent		0
Other financing activities		(330)	(312)
Net cash provided by financing activities of continuing operations		14,528	1,574
Effect of exchange rate changes on cash and due from banks		0	0
Change in cash, due from banks and deposits with banks		5	(1,505)
Cash, due from banks and deposits with banks at beginning of period		3,517	4,516
Cash, due from banks and deposits with banks at end of period		3,522	3,011
Cash and due from banks		22	11
Deposits with banks, net of allowance		3,500	3,000
Cash, due from banks and deposits with banks at end of period		3,522	3,011	3,517
Supplemental disclosure of cash flow information for continuing operations
Cash paid (received) during the period for income taxes		(13)	99
Cash paid during the period for interest		1,305	126
Non-cash investing and financing activities
Decrease in net loans associated with significant disposals reclassified to HFS		0
Decrease in goodwill associated with significant disposals reclassified to HFS		0
Transfers to loans HFS (Other assets) from loans		0	0
Decrease in deposits associated with significant disposals reclassified to HFS		0
Decrease in long-term debt associated with significant disposals reclassified to HFS		0
Reportable legal entities | CGMHI
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities of continuing operations		(3,757)	12,638
Available-for-sale debt securities
Purchases of investments		0	0
Proceeds from sales of investments		0	0
Proceeds from maturities of investments		0	0
Held-to-maturity debt securities
Purchases of investments		0	0
Proceeds from maturities of investments		0	0
Change in loans		0	0
Proceeds from sales and securitizations of loans		0	0
Change in securities borrowed and purchased under agreements to resell		(15,750)	(21,547)
Changes in investments and advances—intercompany		(2,369)	(2,991)
Other investing activities		0	(23)
Net cash used in investing activities of continuing operations		(18,119)	(24,561)
Cash flows from financing activities of continuing operations
Dividends paid		(259)	(115)
Issuance of preferred stock			0
Redemption of preferred stock			0
Treasury stock acquired		0	0
Proceeds (repayments) from issuance of long-term debt, net		5,645	3,172
Proceeds (repayments) from issuance of long-term debt—intercompany, net		1,763	5,702
Change in deposits		0	0
Change in securities loaned and sold under agreements to repurchase		5,220	3,752
Change in short-term borrowings		3,158	551
Net change in short-term borrowings and other advances—intercompany		6,621	(405)
Capital contributions from (to) parent		250
Other financing activities		0	0
Net cash provided by financing activities of continuing operations		22,398	12,657
Effect of exchange rate changes on cash and due from banks		0	0
Change in cash, due from banks and deposits with banks		522	734
Cash, due from banks and deposits with banks at beginning of period		26,665	20,112
Cash, due from banks and deposits with banks at end of period		27,187	20,846
Cash and due from banks		8,484	6,605
Deposits with banks, net of allowance		18,703	14,241
Cash, due from banks and deposits with banks at end of period		27,187	20,846	26,665
Supplemental disclosure of cash flow information for continuing operations
Cash paid (received) during the period for income taxes		(10)	31
Cash paid during the period for interest		522	634
Non-cash investing and financing activities
Decrease in net loans associated with significant disposals reclassified to HFS		0
Decrease in goodwill associated with significant disposals reclassified to HFS		0
Transfers to loans HFS (Other assets) from loans		0	0
Decrease in deposits associated with significant disposals reclassified to HFS		0
Decrease in long-term debt associated with significant disposals reclassified to HFS		0
Reportable legal entities | Other Citigroup subsidiaries and eliminations
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities of continuing operations		(5,180)	15,526
Available-for-sale debt securities
Purchases of investments		(66,115)	(48,998)
Proceeds from sales of investments		57,084	45,960
Proceeds from maturities of investments		28,333	30,003
Held-to-maturity debt securities
Purchases of investments		(28,406)	(62,067)
Proceeds from maturities of investments		2,775	5,085
Change in loans		(9,643)	9,933
Proceeds from sales and securitizations of loans		676	323
Change in securities borrowed and purchased under agreements to resell		(2,372)	1,187
Changes in investments and advances—intercompany		12,285	1,104
Other investing activities		(1,105)	(790)
Net cash used in investing activities of continuing operations		(6,488)	(18,260)
Cash flows from financing activities of continuing operations
Dividends paid		259	115
Issuance of preferred stock			0
Redemption of preferred stock			0
Treasury stock acquired		0	0
Proceeds (repayments) from issuance of long-term debt, net		(3,485)	(9,049)
Proceeds (repayments) from issuance of long-term debt—intercompany, net		(1,763)	(5,702)
Change in deposits		34,816	20,304
Change in securities loaned and sold under agreements to repurchase		7,989	15,891
Change in short-term borrowings		(987)	2,022
Net change in short-term borrowings and other advances—intercompany		(15,151)	(4,557)
Capital contributions from (to) parent		(250)
Other financing activities		0	0
Net cash provided by financing activities of continuing operations		21,428	19,024
Effect of exchange rate changes on cash and due from banks		(233)	(452)
Change in cash, due from banks and deposits with banks		9,527	15,838
Cash, due from banks and deposits with banks at beginning of period		231,851	284,987
Cash, due from banks and deposits with banks at end of period		241,378	300,825
Cash and due from banks		19,262	19,588
Deposits with banks, net of allowance		222,116	281,237
Cash, due from banks and deposits with banks at end of period		241,378	300,825	231,851
Supplemental disclosure of cash flow information for continuing operations
Cash paid (received) during the period for income taxes		654	820
Cash paid during the period for interest		955	629
Non-cash investing and financing activities
Decrease in net loans associated with significant disposals reclassified to HFS		14,970
Decrease in goodwill associated with significant disposals reclassified to HFS		715
Transfers to loans HFS (Other assets) from loans		328	636
Decrease in deposits associated with significant disposals reclassified to HFS		18,334
Decrease in long-term debt associated with significant disposals reclassified to HFS		28
Consolidating adjustments
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities of continuing operations		0	0
Available-for-sale debt securities
Purchases of investments		0	0
Proceeds from sales of investments		0	0
Proceeds from maturities of investments		0	0
Held-to-maturity debt securities
Purchases of investments		0	0
Proceeds from maturities of investments		0	0
Change in loans		0	0
Proceeds from sales and securitizations of loans		0	0
Change in securities borrowed and purchased under agreements to resell		0	0
Changes in investments and advances—intercompany		0	0
Other investing activities		0	0
Net cash used in investing activities of continuing operations		0	0
Cash flows from financing activities of continuing operations
Dividends paid		0	0
Issuance of preferred stock			0
Redemption of preferred stock			0
Treasury stock acquired		0	0
Proceeds (repayments) from issuance of long-term debt, net		0	0
Proceeds (repayments) from issuance of long-term debt—intercompany, net		0	0
Change in deposits		0	0
Change in securities loaned and sold under agreements to repurchase		0	0
Change in short-term borrowings		0	0
Net change in short-term borrowings and other advances—intercompany		0	0
Capital contributions from (to) parent		0
Other financing activities		0	0
Net cash provided by financing activities of continuing operations		0	0
Effect of exchange rate changes on cash and due from banks		0	0
Change in cash, due from banks and deposits with banks		0	0
Cash, due from banks and deposits with banks at beginning of period		0	0
Cash, due from banks and deposits with banks at end of period		0	0
Cash and due from banks		0	0
Deposits with banks, net of allowance		0	0
Cash, due from banks and deposits with banks at end of period		0	0	$ 0
Supplemental disclosure of cash flow information for continuing operations
Cash paid (received) during the period for income taxes		0	0
Cash paid during the period for interest		0	0
Non-cash investing and financing activities
Decrease in net loans associated with significant disposals reclassified to HFS		0
Decrease in goodwill associated with significant disposals reclassified to HFS		0
Transfers to loans HFS (Other assets) from loans		0	$ 0
Decrease in deposits associated with significant disposals reclassified to HFS		0
Decrease in long-term debt associated with significant disposals reclassified to HFS		$ 0

[1] Citi has revised the Consolidated Statement of Cash Flows to present purchases of investments, sales of investments and proceeds from maturities of investments separately between available-for-sale debt securities and held-to-maturity debt securities. Citi had no sales of held-to-maturity debt securities during the periods presented.

[2] Operating and finance lease right-of-use assets and lease liabilities represent non-cash investing and financing activities, respectively, and are not included in the non-cash investing activities presented here. See Note 22 for more information and balances as of March 31, 2022.

[3] See Note 2 for further information on significant disposals.