PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS - Aggregate Notional Amount of Derivatives (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Notional Amount of Derivatives	$ 3,081	$ 2,720
Equity index instruments
Defined Benefit Plan Disclosure [Line Items]
Notional Amount of Derivatives	500	361
Forward contracts
Defined Benefit Plan Disclosure [Line Items]
Notional Amount of Derivatives	523	535
Swaps
Defined Benefit Plan Disclosure [Line Items]
Notional Amount of Derivatives	$ 2,058	$ 1,824