XML 201 R143.htm IDEA: XBRL DOCUMENT v3.8.0.1
Employee Benefit Plans - Change Plan Assets (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]    
Employer contributions $ 280  
Pension Benefits    
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]    
Fair value of plan assets — beginning of year 4,678 $ 4,430
Actual return on plan assets 549 250
Employer contributions 280 301
Benefits paid (248) (279)
Expenses paid (21) (24)
Settlements (1,647) 0
Foreign exchange adjustment 1 0
Fair value of plan assets — end of year 3,592 4,678
Funded status — end of year (784) (972)
Other Postretirement Benefits    
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]    
Fair value of plan assets — beginning of year 138 162
Actual return on plan assets 11 9
Employer contributions 0 0
Benefits paid (35) (33)
Expenses paid 0 0
Settlements 0 0
Foreign exchange adjustment 0 0
Fair value of plan assets — end of year 114 138
Funded status — end of year $ (142) $ (134)