GOODWILL AND INTANGIBLE ASSETS (Details) (USD $) In Millions	3 Months Ended
Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011
Goodwill.
Balance of goodwill at beginning of period	$ 26,621	$ 26,339	$ 26,152
Foreign exchange translation	(1,184)	292	345
Smaller acquisitions/divestitures and other	59	(10)	(11)
Discontinued operations			(147)
Balance of goodwill at end of period	$ 25,496	$ 26,621	$ 26,339

This element represents the net changes to the recorded value of goodwill due to acquisitions or divestitures, purchase accounting adjustments and other adjustments needed to revise the carrying amount of goodwill.

Name:	c_GoodwillAcquisitionsDivestituresPurchaseAccountingAdjustmentsAndOther
Namespace Prefix:	c
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This element represents the net changes to the recorded value of goodwill due to foreign currency translation adjustments.

+ Details

Name:	c_GoodwillTranslationAdjustments
Namespace Prefix:	c
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Carrying amount as of the balance sheet date, which is the cumulative amount paid, adjusted for any amortization recognized prior to adoption of FAS 142 and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 43

+ Details

Name:	us-gaap_Goodwill
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ Details

Name:	us-gaap_GoodwillRollForward
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Write-off of the carrying amount of goodwill associated with all or a portion of a reporting unit that is sold in the period.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 45

-Subparagraph e(3)

+ Details

Name:	us-gaap_GoodwillWrittenOffRelatedToSaleOfBusinessUnit
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration