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, 2019
Dec. 31, 2018
Pension Plan [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Percentage of Plan Assets 100.00% 100.00%
Target Allocation, Percentage, Next Fiscal Year 100.00%  
Pension Plan [Member] | Equity Securities [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Percentage of Plan Assets 44.00% 38.90%
Target Allocation, Percentage, Next Fiscal Year 45.00%  
Pension Plan [Member] | Fixed Income Investments [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Percentage of Plan Assets 26.10% 26.00%
Target Allocation, Percentage, Next Fiscal Year 28.00%  
Pension Plan [Member] | Hedge Funds [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Percentage of Plan Assets 5.40% 5.40%
Target Allocation, Percentage, Next Fiscal Year 5.00%  
Pension Plan [Member] | Private Equity Funds [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Percentage of Plan Assets 6.60% 6.20%
Target Allocation, Percentage, Next Fiscal Year 7.00%  
Pension Plan [Member] | Structured Finance [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Percentage of Plan Assets 7.00% 11.40%
Target Allocation, Percentage, Next Fiscal Year 7.50%  
Pension Plan [Member] | Real Estate [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Percentage of Plan Assets 9.40% 10.30%
Target Allocation, Percentage, Next Fiscal Year 7.50%  
Pension Plan [Member] | Cash [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Percentage of Plan Assets 1.50% 1.80%
Target Allocation, Percentage, Next Fiscal Year 0.00%  
Other Postretirement Benefits Plan [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Percentage of Plan Assets 100.00% 100.00%
Target Allocation, Percentage, Next Fiscal Year 100.00%  
Other Postretirement Benefits Plan [Member] | Equity Securities [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Percentage of Plan Assets 7.20% 8.10%
Target Allocation, Percentage, Next Fiscal Year 8.00%  
Other Postretirement Benefits Plan [Member] | Fixed Income Investments [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Percentage of Plan Assets 79.80% 77.00%
Target Allocation, Percentage, Next Fiscal Year 80.00%  
Other Postretirement Benefits Plan [Member] | Hedge Funds [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Percentage of Plan Assets 4.80% 4.70%
Target Allocation, Percentage, Next Fiscal Year 4.00%  
Other Postretirement Benefits Plan [Member] | Private Equity Funds [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Percentage of Plan Assets 0.70% 1.20%
Target Allocation, Percentage, Next Fiscal Year 3.00%  
Other Postretirement Benefits Plan [Member] | Structured Finance [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Percentage of Plan Assets 2.10% 3.50%
Target Allocation, Percentage, Next Fiscal Year 2.00%  
Other Postretirement Benefits Plan [Member] | Real Estate [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Percentage of Plan Assets 5.40% 5.40%
Target Allocation, Percentage, Next Fiscal Year 3.00%  
Other Postretirement Benefits Plan [Member] | Cash [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Percentage of Plan Assets 0.00% 0.10%
Target Allocation, Percentage, Next Fiscal Year 0.00%