DEBT (Details 3) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2011
Trust Securities
Liquidation value	$ 17,652
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	17,778
Citigroup Capital III
Trust Securities
Securities issued (in shares)	194,053
Liquidation value	194
Coupon rate (as a percent)	0.07625
Common shares issued to parent (in shares)	6,003
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	200
Citigroup Capital VII
Trust Securities
Securities issued (in shares)	35,885,898
Liquidation value	897
Coupon rate (as a percent)	0.07125
Common shares issued to parent (in shares)	1,109,874
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	925
Citigroup Capital VIII
Trust Securities
Securities issued (in shares)	43,651,597
Liquidation value	1,091
Coupon rate (as a percent)	0.06950
Common shares issued to parent (in shares)	1,350,050
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	1,125
Citigroup Capital IX
Trust Securities
Securities issued (in shares)	33,874,813
Liquidation value	847
Coupon rate (as a percent)	0.06000
Common shares issued to parent (in shares)	1,047,675
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	873
Citigroup Capital X
Trust Securities
Securities issued (in shares)	14,757,823
Liquidation value	369
Coupon rate (as a percent)	0.06100
Common shares issued to parent (in shares)	456,428
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	380
Citigroup Capital XI
Trust Securities
Securities issued (in shares)	18,387,128
Liquidation value	460
Coupon rate (as a percent)	0.06000
Common shares issued to parent (in shares)	568,675
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	474
Citigroup Capital XII
Trust Securities
Securities issued (in shares)	92,000,000
Liquidation value	2,300
Coupon rate (as a percent)	0.08500
Common shares issued to parent (in shares)	25
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	2,300
Citigroup Capital XIII
Trust Securities
Securities issued (in shares)	89,840,000
Liquidation value	2,246
Coupon rate (as a percent)	0.07875
Common shares issued to parent (in shares)	25
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	2,246
Citigroup Capital XIV
Trust Securities
Securities issued (in shares)	12,227,281
Liquidation value	306
Coupon rate (as a percent)	0.06875
Common shares issued to parent (in shares)	40,000
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	307
Citigroup Capital XV
Trust Securities
Securities issued (in shares)	25,210,733
Liquidation value	630
Coupon rate (as a percent)	0.06500
Common shares issued to parent (in shares)	40,000
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	631
Citigroup Capital XVI
Trust Securities
Securities issued (in shares)	38,148,947
Liquidation value	954
Coupon rate (as a percent)	0.06450
Common shares issued to parent (in shares)	20,000
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	954
Citigroup Capital XVII
Trust Securities
Securities issued (in shares)	28,047,927
Liquidation value	701
Coupon rate (as a percent)	0.06350
Common shares issued to parent (in shares)	20,000
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	702
Citigroup Capital XVIII
Trust Securities
Securities issued (in shares)	99,901
Liquidation value	156
Coupon rate (as a percent)	0.06829
Common shares issued to parent (in shares)	50
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	156
Citigroup Capital XIX
Trust Securities
Securities issued (in shares)	22,771,968
Liquidation value	569
Coupon rate (as a percent)	0.07250
Common shares issued to parent (in shares)	20,000
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	570
Citigroup Capital XX
Trust Securities
Securities issued (in shares)	17,709,814
Liquidation value	443
Coupon rate (as a percent)	0.07875
Common shares issued to parent (in shares)	20,000
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	443
Citigroup Capital XXI
Trust Securities
Securities issued (in shares)	2,345,801
Liquidation value	2,346
Coupon rate (as a percent)	0.08300
Common shares issued to parent (in shares)	500
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	2,346
Citigroup Capital XXXIII
Trust Securities
Securities issued (in shares)	3,025,000
Liquidation value	3,025
Coupon rate (as a percent)	0.08000
Common shares issued to parent (in shares)	100
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	3,025
Adam Capital Trust III
Trust Securities
Securities issued (in shares)	17,500
Liquidation value	18
Description of coupon rate basis	three months LIBOR
Coupon rate, basis spread (as a percent)	0.0335
Common shares issued to parent (in shares)	542
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	18
Adam Statutory Trust III
Trust Securities
Securities issued (in shares)	25,000
Liquidation value	25
Description of coupon rate basis	three months LIBOR
Coupon rate, basis spread (as a percent)	0.0325
Common shares issued to parent (in shares)	774
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	26
Adam Statutory Trust IV
Trust Securities
Securities issued (in shares)	40,000
Liquidation value	40
Description of coupon rate basis	three months LIBOR
Coupon rate, basis spread (as a percent)	0.0295
Common shares issued to parent (in shares)	1,238
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	41
Adam Statutory Trust V
Trust Securities
Securities issued (in shares)	35,000
Liquidation value	35
Description of coupon rate basis	three months LIBOR
Coupon rate, basis spread (as a percent)	0.0279
Common shares issued to parent (in shares)	1,083
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	36
Citigroup Capital XXXII
Trust Securities
Coupon rate (as a percent)	0.03953
Exchanged trust securities for senior notes	$ 1,875