CONCENTRATIONS OF CREDIT RISK (Details) - Total investments - Geographic - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
U.S.
Concentration Risk [Line Items]
Credit exposure from investment securities, loans and trading assets	$ 227.8	$ 228.5
GERMANY
Concentration Risk [Line Items]
Credit exposure from investment securities, loans and trading assets	38.3	26.7
JAPAN
Concentration Risk [Line Items]
Credit exposure from investment securities, loans and trading assets	25.8	27.3
State and Municipalities
Concentration Risk [Line Items]
Credit exposure from investment securities, loans and trading assets	$ 30.6	$ 30.7