PENSION AND OTHER POSTRETIREMENT BENEFITS - Additional Information (Details)	12 Months Ended
	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets, measurement period	10 years
Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	31.00%
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	31.00%
Other
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	38.00%