PRINCIPAL TRANSACTIONS (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Principal transactions revenue
Principal transactions revenue	$ 1,840	$ 1,971
Interest rate risks
Principal transactions revenue
Principal transactions revenue	807	1,197
Foreign exchange contracts
Principal transactions revenue
Principal transactions revenue	613	86
Equity risk
Principal transactions revenue
Principal transactions revenue	50	114
Commodity and other contracts
Principal transactions revenue
Principal transactions revenue	144	317
Credit products and risks
Principal transactions revenue
Principal transactions revenue	226	257
Citicorp | Operating Segments
Principal transactions revenue
Principal transactions revenue	1,829	1,932
Global Consumer Banking | Operating Segments
Principal transactions revenue
Principal transactions revenue	145	156
Institutional Clients Group | Operating Segments
Principal transactions revenue
Principal transactions revenue	1,574	2,197
Corporate/Other | Operating Segments
Principal transactions revenue
Principal transactions revenue	110	(421)
Citi Holdings | Operating Segments
Principal transactions revenue
Principal transactions revenue	$ 11	$ 39