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Retirement, Other Postretirement Benefits, And Defined Contribution Plans (Plan Assets, Asset Allocations Targets) (Details)
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Domestic Equity Securities [Member] | Non-Taxables [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Target 39.00%  
Range, Minimum 34.00%  
Range, Maximum 44.00%  
Postretirement Asset Allocation 40.00% 40.00%
International Equity Securities [Member] | Non-Taxables [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Target 26.00%  
Range, Minimum 21.00%  
Range, Maximum 31.00%  
Postretirement Asset Allocation 27.00% 24.00%
Fixed Income Securities [Member] | Non-Taxables [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Target 35.00%  
Range, Minimum 30.00%  
Range, Maximum 40.00%  
Postretirement Asset Allocation 33.00% 36.00%
Other Securities [Member] | Non-Taxables [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Target 0.00%  
Range, Minimum 0.00%  
Range, Maximum 5.00%  
Postretirement Asset Allocation 0.00% 0.00%
Qualified Pension And Other Postretirement Plans [Member] | Domestic Equity Securities [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Target 45.00%  
Range, Minimum 37.00%  
Range, Maximum 53.00%  
Postretirement Asset Allocation 46.00% 45.00%
Qualified Pension And Other Postretirement Plans [Member] | International Equity Securities [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Target 20.00%  
Range, Minimum 16.00%  
Range, Maximum 24.00%  
Postretirement Asset Allocation 20.00% 19.00%
Qualified Pension And Other Postretirement Plans [Member] | Fixed Income Securities [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Target 35.00%  
Range, Minimum 32.00%  
Range, Maximum 38.00%  
Postretirement Asset Allocation 33.00% 35.00%
Qualified Pension And Other Postretirement Plans [Member] | Other Securities [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Target 0.00%  
Range, Minimum 0.00%  
Range, Maximum 10.00%  
Postretirement Asset Allocation 1.00% 1.00%