CONTINGENCIES (Details) (USD $)		1 Months Ended			9 Months Ended	48 Months Ended	9 Months Ended
	Sep. 30, 2011	Oct. 31, 2011 Subprime Mortgage-Related Litigation and Other Matters	Sep. 30, 2011 Subprime Mortgage-Related Litigation and Other Matters lawsuit	Oct. 19, 2011 Subprime Mortgage-Related Litigation and Other Matters	Sep. 30, 2011 Residential Mortgage-Backed Securities Investor Actions and Repurchase Claims	Dec. 31, 2008 Residential Mortgage-Backed Securities Investor Actions and Repurchase Claims	Sep. 30, 2011 KIKOs CKI decision lawsuit
CONTINGENCIES
Possible loss, high end of the range	$ 4,000,000,000
Contingencies
Amount of disgorgement		160,000,000
Amount of prejudgment interest		30,000,000
Amount of civil penalty which Citigroup agreed to pay				95,000,000
Investment in Citigroup by Abu Dhabi Investment Authority (ADIA)		7,500,000,000
Private-label mortgage-backed securitization transactions sponsored by Citigroup affiliates					35,000,000,000	91,000,000,000
Losses to date on private-label mortgage-backed securitization transactions sponsored by Citigroup affiliates					9,300,000,000
Lawsuits against Citigroup, number			4
Number civil lawsuits filed by small and medium-sized enterprises							83
Number of decision rendered at district court level							78
Numbers of decision prevailed							62
Number of decisions awarded to plaintiff for portion of damages sought							16
Total damages awarded							$ 19,500,000
Number of adverse decision against which appeal is made							16