v2.4.0.6
Employee Benefit Plans (Assumed Health Care Cost Trend Rates Used to Determine the Postretirement Benefit Obligations) (Details)
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Health care cost trend rate assumed for next year:    
Rate to which the cost trend rate is assumed to decline (ultimate trend rate) 4.50% 4.50%
Year that the rate reaches the ultimate trend rate 2029  
Medical | Minimum
   
Health care cost trend rate assumed for next year:    
Health care cost trend rate assumed for next year 6.93% 6.95%
Medical | Maximum
   
Health care cost trend rate assumed for next year:    
Health care cost trend rate assumed for next year 7.53% 7.68%
Prescription
   
Health care cost trend rate assumed for next year:    
Health care cost trend rate assumed for next year 8.66% 9.08%