ALLOWANCE FOR CREDIT LOSSES (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013		Dec. 31, 2013
Allowance for credit losses
Allowance for loan losses at beginning of period	$ 18,923		$ 23,727		$ 19,648		$ 25,455
Charge-offs	(2,812)		(3,257)		(5,795)		(6,701)
Recoveries	623		649		1,167		1,215
Replenishment of net charge-offs	2,189		2,608		4,628		5,486
Net reserve builds (releases)	(521)		(642)		(1,081)		(948)
Net specific reserve builds (releases)	(89)		(139)		(175)		(497)
Other	(423)	[1]	(1,366)	[1]	(502)	[1]	(2,430)	[1]
Allowance for loan losses at the end of year	17,890		21,580		17,890		21,580
Allowance for loan losses:
Determined in accordance with ASC 450-20	13,197				13,197				14,634
Determined in accordance with ASC 310-10-35	4,583				4,583				4,901
Determined in accordance with ASC 310-30	110				110				113
Total allowance for loan losses	17,890		21,580		17,890		21,580
Loans, net of unearned income:
Loans collectively evaluated for impairment in accordance with ASC 450-20	638,382				638,382				633,679
Loans individually evaluated for impairment in accordance with ASC 310-10-35	23,743				23,743				26,015
Loans acquired with deteriorated credit quality in accordance with ASC 310-30	575				575				749
Loans held at fair value	4,804				4,804				5,029
Loans, net of unearned income	667,504				667,504				665,472
Corporate
Allowance for credit losses
Allowance for loan losses at beginning of period	2,472		2,779		2,584		2,776
Charge-offs	(47)		(97)		(221)		(157)
Recoveries	36		52		65		67
Replenishment of net charge-offs	11		45		156		90
Net reserve builds (releases)	(26)		(98)		(127)		(129)
Net specific reserve builds (releases)	(75)		30		(85)		72
Other	(1)		(3)		(2)		(11)
Allowance for loan losses at the end of year	2,370		2,708		2,370		2,708
Allowance for loan losses:
Determined in accordance with ASC 450-20	2,103				2,103				2,232
Determined in accordance with ASC 310-10-35	183				183				268
Determined in accordance with ASC 310-30	84				84				84
Total allowance for loan losses	2,370		2,708		2,370		2,708
Loans, net of unearned income:
Loans collectively evaluated for impairment in accordance with ASC 450-20	276,784				276,784				265,230
Loans individually evaluated for impairment in accordance with ASC 310-10-35	1,512				1,512				2,222
Loans acquired with deteriorated credit quality in accordance with ASC 310-30	105				105				117
Loans held at fair value	4,758				4,758				4,072
Loans, net of unearned income	283,159				283,159				271,641
Consumer
Allowance for credit losses
Allowance for loan losses at beginning of period	16,451		20,948		17,064		22,679
Charge-offs	(2,765)		(3,160)		(5,574)		(6,544)
Recoveries	587		597		1,102		1,148
Replenishment of net charge-offs	2,178		2,563		4,472		5,396
Net reserve builds (releases)	(495)		(544)		(954)		(819)
Net specific reserve builds (releases)	(14)		(169)		(90)		(569)
Other	(422)		(1,363)		(500)		(2,419)
Allowance for loan losses at the end of year	15,520		18,872		15,520		18,872
Allowance for loan losses:
Determined in accordance with ASC 450-20	11,094				11,094				12,402
Determined in accordance with ASC 310-10-35	4,400				4,400				4,633
Determined in accordance with ASC 310-30	26				26				29
Total allowance for loan losses	15,520		18,872		15,520		18,872
Loans, net of unearned income:
Loans collectively evaluated for impairment in accordance with ASC 450-20	361,598				361,598				368,449
Loans individually evaluated for impairment in accordance with ASC 310-10-35	22,231	[2],[3],[4]			22,231	[2],[3],[4]			23,793
Loans acquired with deteriorated credit quality in accordance with ASC 310-30	470				470				632
Loans held at fair value	46				46				957
Loans, net of unearned income	$ 384,345				$ 384,345				$ 393,831

[1] The second quarter of 2014 includes a reduction of approximately $480 million related to the sale or transfers to held-for-sale (HFS) of various loan portfolios, including a reduction of approximately $204 million and $177 million related to the transfers to HFS of businesses in Greece and Spain and $29 million related to the sale of the Honduras business, and $66 million related to a transfer of a real estate loan portfolio to HFS. These amounts are partially offset by foreign currency translation on the entire allowance balance. The first quarter of 2014 includes reductions of approximately $79 million related to the sale or transfer to HFS of various loan portfolios. The second quarter of 2013 includes a reduction of approximately $650 million related to the sale or transfer to HFS of various U.S. loan portfolios and a reduction of approximately $360 million related to the transfer of Credicard to discontinued operations held for sale. Additionally, a reduction of approximately $90 million related to a transfer to HFS of a loan portfolio in Greece and a reduction of approximately $220 million related to foreign currency translation. The first quarter of 2013 includes reductions of approximately $855 million related to the sale or transfer to HFS of various U.S. loan portfolios and a reduction of approximately $165 million related to a transfer to HFS of a loan portfolio in Greece.

[2] $2,106 million of residential first mortgages, $564 million of home equity loans and $86 million of commercial market loans do not have a specific allowance.

[3] Recorded investment in a loan includes net deferred loan fees and costs, unamortized premium or discount and direct write-downs and includes accrued interest only on credit card loans.

[4] Prior to 2008, the Company’s financial accounting systems did not separately track impaired smaller-balance, homogeneous consumer loans whose terms were modified due to the borrowers’ financial difficulties and where it was determined that a concession was granted to the borrower. Smaller-balance consumer loans modified since January 1, 2008 amounted to $21.9 billion at June 30, 2014. However, information derived from Citi’s risk management systems indicates that the amounts of outstanding modified loans, including those modified prior to 2008, approximated $22.5 billion at June 30, 2014.