SECURITIZATIONS AND VARIABLE INTEREST ENTITIES - Carrying Amounts and Classifications of Consolidated Assets (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Variable Interest Entity
Cash	$ 21,880,000,000us-gaap_CashAndDueFromBanks	$ 32,108,000,000us-gaap_CashAndDueFromBanks	$ 33,380,000,000us-gaap_CashAndDueFromBanks	$ 29,885,000,000us-gaap_CashAndDueFromBanks
Trading account assets	302,983,000,000us-gaap_TradingSecurities	296,786,000,000us-gaap_TradingSecurities
Investments	326,815,000,000c_InvestmentsExcludingTradingSecurities	333,443,000,000c_InvestmentsExcludingTradingSecurities
Total loans, net	606,456,000,000	628,641,000,000
Other assets	136,040,000,000us-gaap_OtherAssets	122,122,000,000us-gaap_OtherAssets
Total assets	1,831,801,000,000us-gaap_Assets	1,842,181,000,000us-gaap_Assets
Consolidated VIEs
Variable Interest Entity
Cash	100,000,000	300,000,000
Trading account assets	600,000,000	700,000,000
Investments	7,600,000,000	8,000,000,000
Total loans, net	85,400,000,000	93,100,000,000
Other assets	4,800,000,000	600,000,000
Total assets	98,500,000,000	102,700,000,000
Short-term borrowings	17,200,000,000	22,700,000,000
Long-term debt	35,300,000,000	40,100,000,000
Other liabilities	4,000,000,000	900,000,000
Total Liabilities	56,500,000,000	63,700,000,000
Significant unconsolidated VIE assets
Variable Interest Entity
Trading account assets	5,300,000,000	7,600,000,000
Investments	2,400,000,000	2,600,000,000
Total loans, net	24,100,000,000	25,000,000,000
Other assets	1,700,000,000	2,000,000,000
Total assets	33,500,000,000	37,200,000,000
Citicorp \| Consolidated VIEs
Variable Interest Entity
Cash	100,000,000	100,000,000
Trading account assets	600,000,000	700,000,000
Investments	7,600,000,000	8,000,000,000
Total loans, net	85,300,000,000	90,600,000,000
Other assets	600,000,000	600,000,000
Total assets	94,200,000,000	100,000,000,000
Short-term borrowings	17,200,000,000	22,700,000,000
Long-term debt	35,200,000,000	38,100,000,000
Other liabilities	700,000,000	800,000,000
Total Liabilities	53,100,000,000	61,600,000,000
Citicorp \| Significant unconsolidated VIE assets
Variable Interest Entity
Trading account assets	5,100,000,000	7,400,000,000
Investments	2,200,000,000	2,400,000,000
Total loans, net	24,000,000,000	24,900,000,000
Other assets	1,600,000,000	1,800,000,000
Total assets	32,900,000,000	36,500,000,000
Citi Holdings \| Consolidated VIEs
Variable Interest Entity
Cash	0	200,000,000
Trading account assets	0	0
Investments	0	0
Total loans, net	100,000,000	2,500,000,000
Other assets	4,200,000,000	0
Total assets	4,300,000,000	2,700,000,000
Short-term borrowings	0	0
Long-term debt	100,000,000	2,000,000,000
Other liabilities	3,300,000,000	100,000,000
Total Liabilities	3,400,000,000	2,100,000,000
Citi Holdings \| Significant unconsolidated VIE assets
Variable Interest Entity
Trading account assets	200,000,000	200,000,000
Investments	200,000,000	200,000,000
Total loans, net	100,000,000	100,000,000
Other assets	100,000,000	200,000,000
Total assets	$ 600,000,000	$ 700,000,000

Sum of the carrying amounts as of the balance sheet date of all investments, excluding trading account assets.

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Also includes long term debt that the creditor have recourse to the general credit of the reporting entity.

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The aggregate carrying amount, as of the balance sheet date, of liabilities not separately disclosed in the balance sheet including other liability that the creditor have recourse to the general credit of the reporting entity.

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Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer including short term debt that the creditor have recourse to the general credit of the reporting entity.

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Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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For banks and other depository institutions: Includes cash on hand (currency and coin), cash items in process of collection, noninterest bearing deposits due from other financial institutions (including corporate credit unions), and noninterest bearing balances with the Federal Reserve Banks, Federal Home Loan Banks and central banks.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

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Amount of investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.

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The carrying amount of the consolidated Variable Interest Entity's liabilities included in the reporting entity's statement of financial position.

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