DEBT - Long-Term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument
Weighted average interest rate	3.49%
Long-term debt, at fair value	$ 206,178	$ 201,275
Weighted average interest rate including effects of derivative contracts	2.63%
Senior debt
Debt Instrument
Long-term debt, at fair value	$ 177,722	172,668
Subordinated debt
Debt Instrument
Long-term debt, at fair value	26,762	26,894
Trust preferred securities
Debt Instrument
Long-term debt, at fair value	1,694	1,713
Citigroup Inc.
Debt Instrument
Long-term debt, at fair value	$ 147,333
Citigroup Inc. \| Senior debt
Debt Instrument
Weighted average interest rate	4.00%
Long-term debt, at fair value	$ 118,881	113,569
Citigroup Inc. \| Subordinated debt
Debt Instrument
Weighted average interest rate	4.48%
Long-term debt, at fair value	$ 26,758	26,875
Citigroup Inc. \| Trust preferred securities
Debt Instrument
Weighted average interest rate	6.90%
Long-term debt, at fair value	$ 1,694	1,713
Bank
Debt Instrument
Long-term debt, at fair value	$ 49,454
Bank \| Senior debt
Debt Instrument
Weighted average interest rate	1.88%
Long-term debt, at fair value	$ 49,454	55,131
Collateralized long-term advances from Federal Home Loan Bank	21,600	17,800
Broker-dealer
Debt Instrument
Long-term debt, at fair value	$ 9,391
Broker-dealer \| Senior debt
Debt Instrument
Weighted average interest rate	2.08%
Long-term debt, at fair value	$ 9,387	3,968
Broker-dealer \| Subordinated debt
Debt Instrument
Weighted average interest rate	0.95%
Long-term debt, at fair value	$ 4	$ 19

Represents the weighted average interest rate at the end of the period after the effect of the derivative contract.

No definition available.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Including both current and noncurrent portions, Federal Home Loan Bank borrowings initially due beyond one year or beyond the normal operating cycle if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64702-112823

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Weighted average interest rate of long-term debt outstanding.

+ References

No definition available.

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