PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Target Allocation and Actual Asset Allocations for Pension and VEBA Plan Assets) (Details)	Dec. 31, 2017	Dec. 31, 2016
Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	100.00%	100.00%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	100.00%
Pension Benefits [Member] | Equity Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	43.60%	43.20%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	45.00%
Pension Benefits [Member] | Fixed Income Investments [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	27.00%	26.40%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	28.00%
Pension Benefits [Member] | Hedge Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	5.00%	5.90%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	5.00%
Pension Benefits [Member] | Private Equity Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	5.30%	5.30%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	7.00%
Pension Benefits [Member] | Structured Finance [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	9.70%	9.30%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	7.50%
Pension Benefits [Member] | Real Estate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	8.70%	9.00%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	7.50%
Pension Benefits [Member] | Cash [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	0.70%	0.90%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0.00%
Other Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	100.00%	100.00%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	100.00%
Other Benefits [Member] | Equity Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	8.70%	8.40%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	8.00%
Other Benefits [Member] | Fixed Income Investments [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	77.70%	78.30%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	80.00%
Other Benefits [Member] | Hedge Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	4.40%	4.40%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	4.00%
Other Benefits [Member] | Private Equity Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	1.50%	1.70%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	3.00%
Other Benefits [Member] | Structured Finance [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	3.00%	2.70%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	2.00%
Other Benefits [Member] | Real Estate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	4.60%	4.40%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	3.00%
Other Benefits [Member] | Cash [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	0.10%	0.10%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0.00%