XML 202 R144.htm IDEA: XBRL DOCUMENT v3.8.0.1
Employee Benefit Plans - Defined Benefit Pension Plans with an Accumulated Benefit Obligations in Excess of Plan Assets (Details) - USD ($)
$ in Millions
Dec. 31, 2017
Dec. 31, 2016
Retirement Benefits [Abstract]    
Projected benefit obligation $ 4,376 $ 5,650
Accumulated benefit obligation 4,376 5,650
Fair value of plan assets $ 3,592 $ 4,678