PENSION AND OTHER POSTRETIREMENT BENEFITS - PLAN ASSETS (Details) - Pension Benefits	12 Months Ended
	Dec. 31, 2016 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Prohibited investments related to capitalization (less than)	$ 250,000,000
Small-cap portion with capitalization levels (as low as)	$ 50,000,000
Equity Securities, U.S. Securities
Defined Benefit Plan Disclosure [Line Items]
Minimum target allocations	28.00%
Maximum target allocations	48.00%
Equity Securities, International Securities
Defined Benefit Plan Disclosure [Line Items]
Minimum target allocations	13.00%
Maximum target allocations	25.00%
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Minimum target allocations	32.00%
Maximum target allocations	42.00%
Other Investments
Defined Benefit Plan Disclosure [Line Items]
Minimum target allocations	0.00%
Maximum target allocations	7.00%