Annual report pursuant to Section 13 and 15(d)

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Target Allocation and Actual Asset Allocations for Pension and VEBA Plan Assets) (Details)

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PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Target Allocation and Actual Asset Allocations for Pension and VEBA Plan Assets) (Details)
Dec. 31, 2018
Dec. 31, 2017
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 38.90% 43.60%
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 26.00% 27.00%
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 5.40% 5.00%
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 6.20% 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 11.40% 9.70%
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 10.30% 8.70%
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 1.80% 0.70%
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 8.10% 8.70%
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 77.00% 77.70%
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 4.70% 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 1.20% 1.50%
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 3.50% 3.00%
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 5.40% 4.60%
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%