PRINCIPAL TRANSACTIONS (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Principal transactions revenue
Principal transactions revenue	$ 3,022	$ 1,840
Interest rate risks
Principal transactions revenue
Principal transactions revenue	1,766	807
Foreign exchange risks
Principal transactions revenue
Principal transactions revenue	588	613
Equity risks
Principal transactions revenue
Principal transactions revenue	188	50
Commodity and other risks
Principal transactions revenue
Principal transactions revenue	90	144
Credit products and risks
Principal transactions revenue
Principal transactions revenue	390	226
Citicorp | Operating Segments
Principal transactions revenue
Principal transactions revenue	3,022	1,840
Global Consumer Banking | Operating Segments
Principal transactions revenue
Principal transactions revenue	149	143
Institutional Clients Group | Operating Segments
Principal transactions revenue
Principal transactions revenue	2,668	1,576
Corporate/Other | Operating Segments
Principal transactions revenue
Principal transactions revenue	$ 205	$ 121