CONDENSED CONSOLIDATING FINANCIAL STATEMENTS - Condensed Consolidating Statement of Cash Flows (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities of continuing operations		$ (3,269)	$ 23,563
Available-for-sale debt securities
Purchases of investments	[1]	(123,528)	(114,240)
Proceeds from sales of investments	[1]	79,952	66,135
Proceeds from maturities of investments	[1]	76,871	62,904
Held-to-maturity debt securities
Purchases of investments	[1]	(34,317)	(87,049)
Proceeds from maturities of investments	[1]	5,821	12,291
Change in loans		(14,790)	(3,088)
Proceeds from sales and securitizations of loans		1,562	869
Proceeds from divestitures	[2]	1,940	0
Change in securities borrowed and purchased under agreements to resell		(34,046)	(14,335)
Changes in investments and advances—intercompany		0	0
Other investing activities		(2,766)	(1,598)
Net cash used in investing activities of continuing operations		(43,301)	(78,111)
Cash flows from financing activities of continuing operations
Dividends paid		(2,514)	(2,663)
Issuance of preferred stock		0	2,300
Redemption of preferred stock		0	(3,785)
Treasury stock acquired		(3,200)	(4,381)
Proceeds (repayments) from issuance of long-term debt, net		31,865	(383)
Proceeds (repayments) from issuance of long-term debt—intercompany, net		0	0
Change in deposits		25,360	29,610
Change in securities loaned and sold under agreements to repurchase		7,187	22,292
Change in short-term borrowings		12,081	1,948
Net change in short-term borrowings and other advances—intercompany		0	0
Capital contributions from (to) parent		0
Other financing activities		(334)	(324)
Net cash provided by financing activities of continuing operations		70,445	44,614
Effect of exchange rate changes on cash and due from banks		(1,878)	(443)
Change in cash, due from banks and deposits with banks		21,997	(10,377)
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		284,030	299,238
Cash and due from banks		24,902	27,117	$ 27,515
Deposits with banks, net of allowance		259,128	272,121	234,518
Cash, due from banks and deposits with banks at end of period		284,030	299,238	262,033
Supplemental disclosure of cash flow information for continuing operations
Cash paid (received) during the period for income taxes		1,661	2,176
Cash paid during the period for interest		6,284	3,926
Non-cash investing and financing activities
Transfer of investment securities from AFS to HTM	[2],[3]	21,522	0
Decrease in net loans associated with divestitures reclassified to HFS	[2],[3]	17,758	0
Decrease in goodwill associated with divestitures reclassified to HFS	[2],[3]	873	0
Transfers to loans HFS (Other assets) from loans	[2],[3]	1,874	961
Decrease in deposits associated with divestitures reclassified to HFS	[2]	20,741	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		(6,787)	1,429
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
Proceeds from divestitures		0
Change in securities borrowed and purchased under agreements to resell		0	0
Changes in investments and advances—intercompany		(2,951)	(2,424)
Other investing activities		0	0
Net cash used in investing activities of continuing operations		(2,951)	(2,424)
Cash flows from financing activities of continuing operations
Dividends paid		(2,514)	(2,663)
Issuance of preferred stock			2,300
Redemption of preferred stock			(3,785)
Treasury stock acquired		(3,200)	(4,381)
Proceeds (repayments) from issuance of long-term debt, net		14,418	7,576
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		1,365	772
Capital contributions from (to) parent		0
Other financing activities		(334)	(324)
Net cash provided by financing activities of continuing operations		9,735	(505)
Effect of exchange rate changes on cash and due from banks		0	0
Change in cash, due from banks and deposits with banks		(3)	(1,500)
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		3,514	3,016
Cash and due from banks		14	16
Deposits with banks, net of allowance		3,500	3,000
Cash, due from banks and deposits with banks at end of period		3,514	3,016	3,517
Supplemental disclosure of cash flow information for continuing operations
Cash paid (received) during the period for income taxes		(15)	(1,437)
Cash paid during the period for interest		1,305	1,287
Non-cash investing and financing activities
Transfer of investment securities from AFS to HTM		0
Decrease in net loans associated with divestitures reclassified to HFS		0
Decrease in goodwill associated with divestitures reclassified to HFS		0
Transfers to loans HFS (Other assets) from loans		0	0
Decrease in deposits associated with divestitures 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		(5,447)	5,912
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
Proceeds from divestitures		0
Change in securities borrowed and purchased under agreements to resell		(27,194)	(14,084)
Changes in investments and advances—intercompany		(16,450)	(7,360)
Other investing activities		(25)	(15)
Net cash used in investing activities of continuing operations		(43,669)	(21,459)
Cash flows from financing activities of continuing operations
Dividends paid		(266)	(187)
Issuance of preferred stock			0
Redemption of preferred stock			0
Treasury stock acquired		0	0
Proceeds (repayments) from issuance of long-term debt, net		21,082	8,446
Proceeds (repayments) from issuance of long-term debt—intercompany, net		11,110	11,040
Change in deposits		0	0
Change in securities loaned and sold under agreements to repurchase		9,282	(9,152)
Change in short-term borrowings		4,947	3,358
Net change in short-term borrowings and other advances—intercompany		1,027	4,885
Capital contributions from (to) parent		250
Other financing activities		1	0
Net cash provided by financing activities of continuing operations		47,433	18,390
Effect of exchange rate changes on cash and due from banks		0	0
Change in cash, due from banks and deposits with banks		(1,683)	2,843
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		24,982	22,955
Cash and due from banks		6,460	6,642
Deposits with banks, net of allowance		18,522	16,313
Cash, due from banks and deposits with banks at end of period		24,982	22,955	26,665
Supplemental disclosure of cash flow information for continuing operations
Cash paid (received) during the period for income taxes		(8)	649
Cash paid during the period for interest		1,869	1,197
Non-cash investing and financing activities
Transfer of investment securities from AFS to HTM		0
Decrease in net loans associated with divestitures reclassified to HFS		0
Decrease in goodwill associated with divestitures reclassified to HFS		0
Transfers to loans HFS (Other assets) from loans		0	0
Decrease in deposits associated with divestitures 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		8,965	16,222
Available-for-sale debt securities
Purchases of investments		(123,528)	(114,240)
Proceeds from sales of investments		79,952	66,135
Proceeds from maturities of investments		76,871	62,904
Held-to-maturity debt securities
Purchases of investments		(34,317)	(87,049)
Proceeds from maturities of investments		5,821	12,291
Change in loans		(14,790)	(3,088)
Proceeds from sales and securitizations of loans		1,562	869
Proceeds from divestitures		1,940
Change in securities borrowed and purchased under agreements to resell		(6,852)	(251)
Changes in investments and advances—intercompany		19,401	9,784
Other investing activities		(2,741)	(1,583)
Net cash used in investing activities of continuing operations		3,319	(54,228)
Cash flows from financing activities of continuing operations
Dividends paid		266	187
Issuance of preferred stock			0
Redemption of preferred stock			0
Treasury stock acquired		0	0
Proceeds (repayments) from issuance of long-term debt, net		(3,635)	(16,405)
Proceeds (repayments) from issuance of long-term debt—intercompany, net		(11,110)	(11,040)
Change in deposits		25,360	29,610
Change in securities loaned and sold under agreements to repurchase		(2,095)	31,444
Change in short-term borrowings		7,134	(1,410)
Net change in short-term borrowings and other advances—intercompany		(2,392)	(5,657)
Capital contributions from (to) parent		(250)
Other financing activities		(1)	0
Net cash provided by financing activities of continuing operations		13,277	26,729
Effect of exchange rate changes on cash and due from banks		(1,878)	(443)
Change in cash, due from banks and deposits with banks		23,683	(11,720)
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		255,534	273,267
Cash and due from banks		18,428	20,459
Deposits with banks, net of allowance		237,106	252,808
Cash, due from banks and deposits with banks at end of period		255,534	273,267	231,851
Supplemental disclosure of cash flow information for continuing operations
Cash paid (received) during the period for income taxes		1,684	2,964
Cash paid during the period for interest		3,110	1,442
Non-cash investing and financing activities
Transfer of investment securities from AFS to HTM		21,522
Decrease in net loans associated with divestitures reclassified to HFS		17,758
Decrease in goodwill associated with divestitures reclassified to HFS		873
Transfers to loans HFS (Other assets) from loans		1,874	961
Decrease in deposits associated with divestitures reclassified to HFS		20,741
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
Proceeds from divestitures		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
Transfer of investment securities from AFS to HTM		0
Decrease in net loans associated with divestitures reclassified to HFS		0
Decrease in goodwill associated with divestitures reclassified to HFS		0
Transfers to loans HFS (Other assets) from loans		0	$ 0
Decrease in deposits associated with divestitures 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] See Note 2 for further information on significant disposals.

[3] 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 June 30, 2022.