This element represents the fair value of total assets for which it has been opted to apply fair value measurement for financial reporting purposes.

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- Definition

The amount of gains and losses from fair value changes in assets, which are elected under fair value option, included in earnings during the period.

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- Definition

The amount of gains and losses from fair value changes in Federal funds purchased and securities loaned or sold under agreements to repurchase, at fair value, which are elected under fair value option, included in earnings during the period.

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- Definition

The amount of gains and losses from fair value changes in Federal funds sold and securities borrowed or purchased under agreements to resell, which are elected under fair value option, included in earnings during the period.

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- Definition

The amount of gains and losses from fair value changes in interest bearing deposit liabilities, which are elected under fair value option, included in earnings during the period.

+ Details

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- Definition

The amount of gains and losses from fair value changes in investments, which are elected under fair value option, included in earnings during the period.

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- Definition

The amount of gains and losses from fair value changes in liabilities, which are elected under fair value option, included in earnings during the period.

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- Definition

The amount of gains and losses from fair value changes in loans receivable, which are elected under fair value option, included in earnings during the period.

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- Definition

The amount of gains and losses from fair value changes in long-term borrowings, at fair value, which are elected under fair value option, included in earnings during the period.

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- Definition

The amount of gains and losses from fair value changes in other assets, which are elected under fair value option, included in earnings during the period.

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- Definition

The amount of gains and losses from fair value changes in short-term borrowings, at fair value, which are elected under fair value option, included in earnings during the period.

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- Definition

The amount of gains and losses from fair value changes in trading account assets, which are elected under fair value option, included in earnings during the period.

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- Definition

The amount of gains and losses from fair value changes in trading account liabilities, at fair value, which are elected under fair value option, included in earnings during the period.

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- Definition

The Fair Value disclosure of the amount shown on the books that a bank with insufficient reserves borrows, at the federal funds rate, from another bank to meet its reserve requirements and the amount of securities that an institution sells and agrees to repurchase at a specified date for a specified price, net of any reductions or offsets.

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- Definition

This element represents the portion of interest-bearing deposits valued at fair value by the entity.

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

This element represents the fair value of total liabilities for which it has been opted to apply fair value measurement for financial reporting purposes.

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Period Type:	instant

- Definition

For an unclassified balance sheet, the Fair Value disclosure of the total of (current and noncurrent) carrying amounts of long-term borrowings as of the balance sheet date, which may include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of long-term debt.

+ Details

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- Definition

This element represents the fair value of other assets for which it has been opted to apply fair value measurement for financial reporting purposes.

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Period Type:	instant

- Definition

Reflects the Fair Value disclosure of 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.

+ Details

Name:	c_ShortTermBorrowingsFairValue
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Period Type:	instant

- Definition

This element represents the fair value of trading account assets for which it has been opted to apply fair value measurement for financial reporting purposes.

+ Details

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Namespace Prefix:	c
Data Type:	xbrli:monetaryItemType
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- Details

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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. The amount shown on an entity's books for federal funds sold and securities borrowed or purchased under agreements to resell.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Audit and Accounting Guide (AAG)
-Number AAG-DEP
-Chapter 14
-Paragraph 4
-IssueDate 2006-05-01

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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents investment securities as of the balance sheet date which may include marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 13

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 12
-Subparagraph a

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 1
-Subparagraph a, f, g
-Article 7

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- Details

Name:	us-gaap_LiabilitiesAbstract
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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents loan receivable as presented on the statement of financial position which may include mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts, or any other loans which are due the Company as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 114
-Paragraph 4

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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents those liabilities that are incurred for the purpose of generating a profit from short-term fluctuations in price as part of a bank's or company's market-making, hedging and proprietary trading. Examples include short positions in securities, derivatives and commodities.

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FAIR VALUE ELECTIONS (Details) (USD $) In Millions															6 Months Ended
FAIR VALUE ELECTIONS (Details) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2011 Fair value, fair value option	Dec. 31, 2010 Fair value, fair value option	Jun. 30, 2011 Fair value, fair value option Corporate loans.	Dec. 31, 2010 Fair value, fair value option Corporate loans.	Jun. 30, 2011 Fair value, fair value option Consumer loans.	Dec. 31, 2010 Fair value, fair value option Consumer loans.	Jun. 30, 2011 Fair value, fair value option Mortgage servicing rights	Dec. 31, 2010 Fair value, fair value option Mortgage servicing rights	Jun. 30, 2011 Fair value, fair value option Certain mortgage loans (HFS)	Dec. 31, 2010 Fair value, fair value option Certain mortgage loans (HFS)	Jun. 30, 2011 Fair value, fair value option Certain equity method investments	Dec. 31, 2010 Fair value, fair value option Certain equity method investments	Jun. 30, 2011 Changes in fair value gains (losses)	Jun. 30, 2010 Changes in fair value gains (losses)	Jun. 30, 2011 Changes in fair value gains (losses) Corporate loans.	Jun. 30, 2010 Changes in fair value gains (losses) Corporate loans.	Jun. 30, 2011 Changes in fair value gains (losses) Consumer loans.	Jun. 30, 2010 Changes in fair value gains (losses) Consumer loans.	Jun. 30, 2011 Changes in fair value gains (losses) Mortgage servicing rights	Jun. 30, 2010 Changes in fair value gains (losses) Mortgage servicing rights	Jun. 30, 2011 Changes in fair value gains (losses) Certain mortgage loans (HFS)	Jun. 30, 2010 Changes in fair value gains (losses) Certain mortgage loans (HFS)	Jun. 30, 2011 Changes in fair value gains (losses) Certain equity method investments	Jun. 30, 2010 Changes in fair value gains (losses) Certain equity method investments
Assets
Federal funds sold and securities borrowed or purchased under agreements to resell, selected portfolios of securities purchased under agreements to resell and securities borrowed	$ 147,401	$ 87,512	$ 147,401	$ 87,512
Federal funds sold and securities borrowed or purchased under agreements to resell, selected portfolios of securities purchased under agreements to resell and securities borrowed															(375)	528
Trading account assets			15,106	14,289
Trading account assets															68	17
Investments	286,642	281,174	843	646
Investments															299	(9)
Loans	4,840	4,372	4,840	4,372	3,418	2,627	1,422	1,745
Loans															(138)	(67)	29	(137)	(167)	70
Other assets			8,628	12,013					4,258	4,554	4,198	7,230	172	229
Other assets															(36)	(1,082)					(99)	(1,198)	73	147	(10)	(31)
Total assets elected under fair value option			176,818	118,832
Total assets Changes in fair value gain (loss) on assets															182	(613)
Liabilities
Interest-bearing deposits			1,751	1,265
Interest-bearing deposits															29	2
Federal funds purchased and securities loaned or sold under agreements to repurchase	125,072	121,193	125,072	121,193
Federal funds purchased and securities loaned or sold under agreements to repurchase Selected portfolios of securities sold under agreements to repurchase and securities loaned															20	91
Trading account liabilities			3,231	3,953
Trading account liabilities															105	145
Short-term borrowings	1,938	2,429	1,938	2,429
Short-term borrowings															65	57
Long-term debt, at fair value	26,999	25,997	26,999	25,997
Long-term debt															49	563
Total liabilities elected under fair value option			158,991	154,837
Fair value option changes in fair value gain (loss) on liabilities															$ 268	$ 858