DEBT - Maturities of Long-Term Debt (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Long-term Debt, Fiscal Year Maturity [Abstract]
2015	$ 31,070
2016	42,128
2017	40,249
2018	22,017
2019	22,117
Thereafter	65,499
Long-term Debt	223,080us-gaap_LongTermDebt	221,116us-gaap_LongTermDebt
Bank
Long-term Debt, Fiscal Year Maturity [Abstract]
2015	14,459
2016	21,248
2017	14,190
2018	9,128
2019	2,146
Thereafter	3,975
Long-term Debt	65,146
Broker-dealer
Long-term Debt, Fiscal Year Maturity [Abstract]
2015	760
2016	708
2017	210
2018	141
2019	1,725
Thereafter	4,878
Long-term Debt	8,422
Citigroup Inc.
Long-term Debt, Fiscal Year Maturity [Abstract]
2015	15,851
2016	20,172
2017	25,849
2018	12,748
2019	18,246
Thereafter	56,646
Long-term Debt	$ 149,512	$ 156,804

Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 7

Reference 2: http://www.xbrl.org/2003/role/presentationRef

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-Topic 210

-SubTopic 10

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 10

-Section 50

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

-Topic 235

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-Section S99

-Paragraph 3

-Subparagraph (SX 210.12-04.(a))

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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