XML 84 R73.htm IDEA: XBRL DOCUMENT v3.8.0.1
Postretirement Benefit Plans (Textuals) (Details) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block    
Other postretirement benefit expense $ 1 $ 1
Amortization of net actuarial loss (less than $1 million) 1 1
Employer contribution to defined benefit plan 6 $ 6
Minimum    
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block    
Additional contributions 14  
Maximum    
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block    
Additional contributions $ 24