INVESTMENTS (Details) (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
Investment Holdings
Investments	$ 325,623			$ 325,623			$ 308,980
Interest and dividends on investments
Taxable interest	1,544		1,381	3,011		2,891
Interest exempt from U.S. federal income tax	147		198	311		370
Dividends	116		108	242		228
Total interest and dividends	1,807		1,687	3,564		3,489
Gross realized investments losses, excluding losses from other-than-temporary impairment
Gross realized investment gains	168		620	460		1,114
Gross realized investment losses	(84)		(369)	(248)		(413)
Net realized gains (losses)	84		251	212		701
Available-for-sale Securities transferred from Held-to-maturity
Carrying value of HTM securities sold	5		318	5		485
Net realized gain (loss) on sale of held-to-maturity securities			(56)			(66)
Carrying value of securities reclassified as available-for-sale	14		300	66		902
OTTI losses on securities reclassified to available-for-sale	(1)		(61)	(9)		(155)
Securities available-for-sale
Amortized cost	291,991			291,991			288,567
Gross unrealized gains	3,242	[1]		3,242	[1]		2,028	[1]
Gross unrealized losses	2,655	[1]		2,655	[1]		4,084	[1]
Fair value	292,578			292,578			286,511
Unrealized loss from impact of minority investments and related allocations and pick up of unrealized losses of AFS securities	3			3
Unrealized gains from impact of minority investments and the related allocations and pick up of unrealized gains and losses of AFS securities							36
Mortgage-backed securities - U.S. government-sponsored agency guaranteed
Securities available-for-sale
Amortized cost	37,295	[2]		37,295	[2]		42,494	[2]
Gross unrealized gains	567	[1],[2]		567	[1],[2]		391	[1],[2]
Gross unrealized losses	317	[1],[2]		317	[1],[2]		888	[1],[2]
Fair value	37,545	[2]		37,545	[2]		41,997	[2]
Mortgage-backed securities - Prime
Securities available-for-sale
Amortized cost	15	[2]		15	[2]		33	[2]
Gross unrealized gains							2	[1],[2]
Gross unrealized losses							3	[1]
Fair value	15	[2]		15	[2]		32	[2]
Mortgage-backed securities - Alt-A
Securities available-for-sale
Amortized cost	2	[2]		2	[2]		84	[2]
Gross unrealized gains							10	[1]
Fair value	2	[2]		2	[2]		94	[2]
Mortgage-backed securities - Subprime
Securities available-for-sale
Amortized cost	0	[2]		0	[2]		12
Fair value	0	[2]		0	[2]		12
Mortgage-backed securities - Non-U.S. residential
Securities available-for-sale
Amortized cost	9,475	[2]		9,475	[2]		9,976	[2]
Gross unrealized gains	95	[1],[2]		95	[1],[2]		95	[1],[2]
Gross unrealized losses	8	[1],[2]		8	[1],[2]		4	[1]
Fair value	9,562	[2]		9,562	[2]		10,067	[2]
Mortgage-backed securities - Commercial
Securities available-for-sale
Amortized cost	516	[2]		516	[2]		455	[2]
Gross unrealized gains	8	[1],[2]		8	[1],[2]		6	[1],[2]
Gross unrealized losses	3	[1],[2]		3	[1],[2]		8	[1],[2]
Fair value	521	[2]		521	[2]		453	[2]
Mortgage-backed securities
Securities available-for-sale
Amortized cost	47,303	[2]		47,303	[2]		53,054	[2]
Gross unrealized gains	670	[1],[2]		670	[1],[2]		504	[1],[2]
Gross unrealized losses	328	[1],[2]		328	[1],[2]		903	[1],[2]
Fair value	47,645	[2]		47,645	[2]		52,655	[2]
U.S. Treasury
Securities available-for-sale
Amortized cost	88,218			88,218			68,891
Gross unrealized gains	475	[1]		475	[1]		476	[1]
Gross unrealized losses	61	[1]		61	[1]		147	[1]
Fair value	88,632			88,632			69,220
Agency obligations
Securities available-for-sale
Amortized cost	15,095			15,095			18,320
Gross unrealized gains	104	[1]		104	[1]		123	[1]
Gross unrealized losses	19	[1]		19	[1]		67	[1]
Fair value	15,180			15,180			18,376
U.S. Treasury and federal agency securities
Securities available-for-sale
Amortized cost	103,313			103,313			87,211
Gross unrealized gains	579	[1]		579	[1]		599	[1]
Gross unrealized losses	80	[1]		80	[1]		214	[1]
Fair value	103,812			103,812			87,596
State and municipal securities
Securities available-for-sale
Amortized cost	13,903	[3]		13,903	[3]		20,761	[3]
Gross unrealized gains	745	[1],[3]		745	[1],[3]		184	[1],[3]
Gross unrealized losses	1,756	[1],[3]		1,756	[1],[3]		2,005	[1],[3]
Fair value	12,892	[3]		12,892	[3]		18,940	[3]
Foreign government
Securities available-for-sale
Amortized cost	95,580			95,580			96,608
Gross unrealized gains	654	[1]		654	[1]		403	[1]
Gross unrealized losses	254	[1]		254	[1]		540	[1]
Fair value	95,980			95,980			96,471
Corporate
Securities available-for-sale
Amortized cost	10,815			10,815			11,039
Gross unrealized gains	270	[1]		270	[1]		210	[1]
Gross unrealized losses	82	[1]		82	[1]		119	[1]
Fair value	11,003			11,003			11,130
Asset-backed securities
Securities available-for-sale
Amortized cost	14,452	[2]		14,452	[2]		15,352	[2]
Gross unrealized gains	54	[1],[2]		54	[1],[2]		42	[1],[2]
Gross unrealized losses	83	[1],[2]		83	[1],[2]		120	[1],[2]
Fair value	14,423	[2]		14,423	[2]		15,274	[2]
Other debt securities
Securities available-for-sale
Amortized cost	711			711			710
Gross unrealized gains							1	[1]
Gross unrealized losses	1	[1]		1	[1]
Fair value	710			710			711
Debt securities
Securities available-for-sale
Amortized cost	286,077			286,077			284,735
Gross unrealized gains	2,972	[1]		2,972	[1]		1,943	[1]
Gross unrealized losses	2,584	[1]		2,584	[1]		3,901	[1]
Fair value	286,465			286,465			282,777
Equity securities
Securities available-for-sale
Amortized cost	5,914			5,914			3,832
Gross unrealized gains	270	[1]		270	[1]		85	[1]
Gross unrealized losses	71	[1]		71	[1]		183	[1]
Fair value	6,113			6,113			3,734
Securities available-for-sale (AFS)
Investment Holdings
Investments	292,578			292,578			286,511
Held-to-maturity Securities
Investment Holdings
Investments	22,330	[4]		22,330	[4]		10,599	[4]
Non-marketable equity securities | Fair value
Investment Holdings
Investments	3,920	[5]		3,920	[5]		4,705	[5]
Non-marketable equity securities | Carried at cost
Investment Holdings
Investments	$ 6,795	[6]		$ 6,795	[6]		$ 7,165	[6]

[1] Gross unrealized gains and losses, as presented, do not include the impact of minority investments and the related allocations and pick-up of unrealized gains and losses of AFS securities. These amounts totaled $3 million of unrealized loss and $36 million of unrealized gains as of June 30, 2014 and December 31, 2013, respectively.

[2] The Company invests in mortgage-backed and asset-backed securities. These securitizations are generally considered VIEs. The Company’s maximum exposure to loss from these VIEs is equal to the carrying amount of the securities, which is reflected in the table above. For mortgage-backed and asset-backed securitizations in which the Company has other involvement, see Note 20 to the Consolidated Financial Statements.

[3] The gross unrealized losses on state and municipal debt securities are primarily attributable to the effects of fair value hedge accounting. Specifically, Citi hedges the LIBOR-benchmark interest rate component of certain fixed-rate tax-exempt state and municipal debt securities utilizing LIBOR-based interest rate swaps. During the hedge period, losses incurred on the LIBOR-hedging swaps recorded in earnings were substantially offset by gains on the state and municipal debt securities attributable to changes in the LIBOR swap rate being hedged. However, because the LIBOR swap rate decreased significantly during the hedge period while the overall fair value of the municipal debt securities was relatively unchanged, the effect of reclassifying fair value gains on these securities from Accumulated other comprehensive income (loss) (AOCI) to earnings, attributable solely to changes in the LIBOR swap rate, resulted in net unrealized losses remaining in AOCI that relate to the unhedged components of these securities.

[4] Recorded at amortized cost less impairment for securities that have credit-related impairment.

[5] Unrealized gains and losses for non-marketable equity securities carried at fair value are recognized in earnings.

[6] Non-marketable equity securities carried at cost primarily consist of shares issued by the Federal Reserve Bank, Federal Home Loan Banks, foreign central banks and various clearing houses of which Citigroup is a member.