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Pension And Other Postretirement Benefit Plans (Weighted-Average Target Pension Asset Allocation And Target Ranges By Major Asset Category) (Details)
12 Months Ended
Mar. 31, 2016
Mar. 31, 2015
Defined Benefit Plan Disclosure [Line Items]    
Target Allocation 100.00%  
Actual Allocation 100.00% 100.00%
Domestic Equity Securities [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Target Allocation 26.00%  
Target Allocation Range, Minimum 16.00%  
Target Allocation Range, Maximum 36.00%  
Actual Allocation 22.40% 25.30%
Fixed Income Securities [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Target Allocation 69.00%  
Target Allocation Range, Minimum 59.00%  
Target Allocation Range, Maximum 79.00%  
Actual Allocation 71.50% 69.10%
Real Estate Funds [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Target Allocation 5.00%  
Target Allocation Range, Minimum 0.00%  
Target Allocation Range, Maximum 10.00%  
Actual Allocation 6.10% 5.60%